A few points here. I commend you for turning to find some help and reassurance. Your realisation that self-diagnosis ought to be avoided is a good idea too.

I have some questions: you have mentioned a therapist and I wonder what kind. Are they a psychologist, social worker, or a counsellor? Pretty much anyone can call themselves a therapist these days hence my curiosity at what you have. This wonder is sparked by your indication your 'therapist' is reluctant to make a diagnosis - this because a therapist (psychologist) is trained to do so. The others are not.

Perhaps a referral to a psychiatrist would be a good idea then.

In the meantime, I can understand the fear of not knowing. Seeing a psychiatrist came as a huge relief to me. Finally I knew what was wrong and could start dealing with it. And even moreso, I for the first time realised that I belonged to a group of people just like me.