I don't have much about autism co-occurring with OCD and if you have identified this in yourself or you've been diagnosed with it then please don't take this as me invalidating either - I'm no expert and I'm certainly not an expert when it comes to you.

My advice for an autistic person who thinks they might have OCD would be to withhold judgment on that front until you have a good grasp of what autism is and how it presents in you in particular.

The reason being that there are a lot of autistic traits that can closely resemble OCD and so I reckon that it's best to do some thorough investigation into your experience before you arrive at a conclusion.

For autistic people, "perseveration" is a phenomenon that is extremely common. This takes on a lot of different forms but on the outside it often looks like ritualistic repetition of behaviours or patterns of speech. (This is going to get a bit normative and a bit pathologising so you're going to have to excuse me for that and you'll have to take this as laying the foundations of understanding perseveration but it's far from the final word on the matter.) These repetitive behaviours are deemed to be problematic or without purpose, e.g. repeating the same "script" each time you meet a particular person where the first time it was purposeful but the repetition of it becomes "useless" or repeating an action beyond its "usefulness" to the task, such as continuing to clean over an already cleaned surface.

Internally perseveration often presents as looping thoughts and thought spirals, which can feel very compulsive too.

The other side of this is that the world is pretty damn chaotic and overwhelming for most autistic people, plus allistic people are operating on an implicit set of rules that we autistic people didn't seem to be provided with, and so we tend to get a great sense of comfort and relief from things which are certain and from repeating patterns of behaviour in a particular way. Breaking from these patterns which provide a sense of security, especially without a good reason, can be distressing because those behaviours are like our own little islands of certainty in an ocean of unpredictability and being without that can be enough to cause a meltdown or a shutdown for an autistic person.

Autistic people tend to be pretty black-and-white thinkers. Some of it is just part of the deal with being autistic and I'd argue that a significant part of it is because an autistic person has probably spent a long time figuring out the best way to perform a procedure to achieve an optimal outcome for themselves, so to them it's the "right" way to do things. (Which is kinda funny when you get two autistic people working together on something but they each have their own different "right" procedure for the task they are doing together - it can lead to a lot of friction.) Breaking from your "right" way of doing something can be frustrating and distressing, which is another thing that can resemble OCD symptoms.

I suppose stimming/stereotypies can look like OCD in some respects as well.

I think that OCD and autistic traits that resemble OCD are generally qualitatively different. I don't experience OCD so I can't speak authoritatively about it but if you are engaging in a behaviour or thought pattern which feels compulsive to you then developing an understanding of how the experience feels for you is really important in distinguishing one from the other.

With perseveration, behaviours might be hard to pull yourself away from but it shouldn't feel particularly emotionally distressing to cease the activity. Sorta like if you're swimming laps in a pool and you achieve your desired number of laps but you decide to keep going for whatever reason (or reps with weights or making something with handicraft... that sort of thing.) If you opt to keep going longer than is "necessary" but you aren't doing this behaviour to keep an impending wave of anxiety at bay then it's probably perseveration not OCD.

On the other hand, if you don't want to perform the behaviour but the thought of stopping it gives you feelings of impending doom and your behaviour is driven by a way to manage or avoid anxiety which is directly connected to the activity in your mind (e.g. "Every time I wash my hands, I must wash them 12 times from start to finish or otherwise I'm going to get sick and die") then that is pretty much squarely OCD. The distinction here is that something like knitting can help alleviate anxiety about other things - work stress, relationship stuff, generalised anxiety - and so it can feel soothing to the point where you want to just sit in your room and spend hours knitting but you aren't going to bring on a panic attack if you put the knitting needles down because you feel like you must do a certain amount of knitting or else.

In a similar way, for autistic people breaking from your "right" way of doing things is going to feel maybe awkward and uncomfortable, and potentially even distressing to a certain degree, but it's really just about having your preferred procedure and/or preferred outcomes. Some people might put socks on before they put on their pants because it provides their ideal outcome - one where your socks sit nicely without having to mess around with them like you would doing it the other way.

For me, one example of this is that I need to put my socks on straight - if I put them on skewed and then twist them to adjust them into place, the tension on my feet is uneven and it's just uncomfortable for me until I take them off, so my strong preference is to put my socks on straight and to take them off and redo the whole process if a sock is misaligned. I don't feel the overwhelming and irresistible compulsion to take my socks off and put them back on a particular number of times. If I straighten a skewed sock on my foot, I can live with it - it's annoying and I don't like it but I don't experience waves of terror or panic associated with it and it doesn't cause intrusive thoughts or anything like that.

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