Battling with imposter syndrome

From reading a few posts on here it seems like this is pretty common but im struggling hard with feeling like a fraud while waiting for my assessment. Im doubting and second guessing whether i have asd or not and the not knowing is bothering me. Some times im absolutely convinced, other times im afraid its all in my head and im seeing things that arent there, this isnt helped by my anxiety issues

As the wait is so long i looked into going private and found a viable way to have an assessment within the next few weeks, but due to the feelings im having im hesitating to book the assessment as im afraid that i may not be asd and then i will have spent a large amount of money on the assessment for nothing. Particularly as i dont have an informant, so this could complicate the assessment. But the NHS list is extremely long and the wait may drive me crazy!

How do i get over these feelings? Im so confused what i should do