Am i overreacting?

Hi guys, I'm new here...so hello all!

Just to set the story....basically, me and my girlfriend have now been together for just over two months. It's both of our's first relationship in two years. We live in the same area and are both the same age.

Here's my dilemma (if it is was one, maybe it is...maybe it isn't - that's why im here).

We started officially going out this summer in August, I knew that come September she was starting a year long hectic uni course which would obviously take up quite a lot of her time. The couple of weeks leading up to September we saw each other very regularly, and stayed at each other's house 3/4 times a week. She did make me aware that come the time she started uni she wouldn't be able to see me as much as we had been, which is completely understandable as she is training for her career. First I thought I'd be lucky if I got to see her once a week if that but it turns out it's not so bad, we see each other maybe twice a week and some night's we see each other for an hour or so. The problem is, lately she's started her placement...and she has been very forward with me in saying I probably wont see her all week due to her not wanting to be tired and boring (which i told her was silly and that it didn't bother me at all) but she's quite adamant about it. Now I know I'm being silly but it's really stressing me out and I don't know what to do about it. I've suffered from severe cases of OCD in the past from the age of 12 to 18....I never told no one or received treatment. Eventually it wore off, but now I often suffer from anxiety. She never knew this about me, but last week we had a bit of a heart to heart and I told her, and I felt so much better about it....as it explains why I act the way I do sometimes.

Anyhow, this past week I have tried to take a new way of dealing with things...if there was something that angered me before I have been trying my very hardest to calm down and realise that what it was that bothered me really wasn't worth worrying about, and it's been working and I felt great. I have barely seen her this week until tonight when we met up for a walk/to hang out a bit. I asked her if we could see each other this weekend and she said probably not as she's going to be very busy preparing for her full week of placement next week, normally something like that (as bad as it sounds) would annoy me slightly...but tonight I really tried to accept it...but she still thought that I reacted as I always do...which did annoy me very much. We walked home and it was pretty awkward and silent and I drove her home at her request, we eventually started speaking in the car and it was ok but I still felt pretty pissed.

When things like this happen and we have a slight fall out and I know that I won't be seeing her for a good few days, it eats me up inside and I end up having anxiety attacks where i smoke relentlessly and get really ratty (this is a problem I know I need to deal with). What Im worried about is that I don't think I can snap out of this way of behaving as much as I want too and im scared that I am going to eventually drive her away from me. I know she's not doing anything Saturday night as she's babysitting a family member...so I don't understand why I can't spend the night with her? as her family really like me. Now I don't know if this is being me irational or not. To whoever's reading this, your probably thinking this one situation is not a big deal at all...but it's happened a few times now and I always act this way. I don't know wether to bottle it up or to open up too her about my frustrations (and then potentially cause an argument)...I know I can come across as needy sometimes, and it's actually got to a point where I'm kinda scared of asking if I can see her...which is not a good thing.

I feel a lot better for writing this down, can anyone offer some advice?

thanks.