Diagnosis Worries..

Hi everyone, 

I'm 27F and I've been waiting for my diagnosis for 2 and a bit years now and finally have my assessment appointment next week! I have so many different feelings about it though, I'm sort of excited that this could finally be it, the answers that I have been looking for for so long, but  what if I'm not? I so desperately want this diagnosis because I have always felt there is something "different" about me and all signs seem to point to this. I studied it in college and worked with teens with ASD too and noticed a number of similarities between the kids I worked with and myself. But I feel like I'm "not Autistic enough" to get the diagnosis and I'm scared that they will tell me I don't have ASD because I'm so sure that there is something and if it isn't ASD then I don't know what else it could be. It almost feels like a test that I have to pass and I need to prepare for it but I don't know how! I know that if they ask me questions I will freeze like a rabbit in headlights, I can't seem to articulate all of the thoughts and feelings I have towards it and say it in actual words. I put as much detail in the "tell us more.." section of the last questionnaire as I could possibly think of but since sending that back to them, I've constantly thought "I should have put that in there too!" but I don't know how to contact them if I were to give them more info, but I don't know what to expect from my appointment, what questions will they ask? What if it's not actually relevant and I come across silly? They said to bring someone with you that knows you well, I'm bringing my Mum, she's always thought I have ASD but she doesn't know an awful lot about it, I've asked about what things in my childhood were significant and she says about my friendships and the way I played, and that I flapped my hands a lot, but other than that, nothing seems to stick out from my childhood and I feel like if I were to have ASD then there would be more to say about it?? Surely someone would have seen more in me, all though school (both primary and secondary) I didn't really struggle with much academically, I was just the "weird kid" and struggled with friendships. There's only a select few people in my life that have noticed things without me telling them. I've never understood the whole concept of masking, well I do, but is it something you can be unaware of doing? Because it's become so normal to you? I don't know, I'm more comfortable at home, and I do things at home that I don't do elsewhere, I suppose it's more of a "I know better" than to do these things outside of my home because it's weird if I do? I have been looking into different stims recently, I have always been a "flapper" but over the past two years (since my partner moved in) I seem to have developed a love for repeating sentences and vocalisations, to a point where I get urges to say them while with other people and have to stop myself because my partner is the only one who understands it, and I'm a chewer, always have been. 

I also worry about what happens next, is it up to me to find out all the ins and outs of what makes me Autistic? Like, I've done my research and I have a list of reasons why I think I am, but that doesn't tell me how to learn to cope, and I'm curious to discover if there's more to it than my list.. Different things that I struggle with that I have not linked to ASD, could they also be because of that? Is there someone that can help me with this? I feel like there's so many different things I struggle with and I'm not sure whether this is why or if it's a separate problem, I suppose apart from talking to you guys, I feel quite alone in this.. I have so many questions and don't know who I can ask. I suppose I just want someone "official" that can validate my worries and feelings because deep down I feel like I'm kidding myself. If they tell me I'm not, I don't have the self confidence to be self-diagnosed, I'd feel like a fraud and I'm stressed because I feel so sure that this is it but if I'm told I'm not I don't know where else to turn to.

I'm sorry for the brain dump, it's just at this point I don't really have anybody else to talk about it to that understands probably more than I do. I can't wait for next week but at the same time I'm so stressed and worried and scared by it.. Any advice?