Actually you don't have to tell doctors anything. Just keep getting him to do labs every few months until you're happy with the numbers.

I want to do this but I have to rely on him to keep my prescription refills up. I definitely could do this if i switch to DIY though.

This doesn't make any sense to me. Why would the injections be different if you did them in different place?

He said it was to make sure I'm using the correct technique for injection but my partner has been doing them for me and she's had actual classes for injection techniques (?) so I dunno what his problem is.