im 17 and scared of diagnosis

I'm scared of diagnosis for 2 main reasons:
1) My mum (the person in charge of the household who gives me little independence etc) has often said that austism assessments are forced. She's forced me to stop many mannerisms (tapping etc) and i doubt she'd let me be diagnosed. She would tell me i'm fine even though she often asks if there's something wrong with me.

2) i feel like because i have the ability to talk to new people when forced to and the fact that although i do better on routine but am fine without, an assessment would come back negative regardless of other things i feel might be different about me.