Should I break-up with her?

Hello,
I was going to write out a detialed story, so I give all the facts and a nice detailed story of our relationship. If this is too much for you to want to read, I have a summary at the bottom you can skip to. I need to know, what will be the best thing for both of us in the end, breaking up, or trying to make it last.

My girlfriend and I have been together for 1 year. I am 19 years old, and she is 18, we are both newly graduated from High School, and currently going to the local community college together. After being together so long, we decided to move in together, which we did 2 weeks ago. For the both of us, this is the first relationship either of us had. After being together this long, I must say we were both happy for the most part. Neither of us are really selfish people, or mean, and we do care and love eachother. It’s just over the time have been together, it seems to me very fight we have had, she starts. I am definatly not blaming it all on her, but my girlfriend (who was on anti-depression medication, but stopped when we started dating) can be a little controlling and can overreact very easily. This I learned to get over, but our share of fights always came from me and hanging out with my friends, although whenever I was wiht my friends, it was always when she was busy, or I had already promised my friends, because she had been busy, yet sometimes she freed herself up unexpectedly, just to get angry at me for being busy. All of these kind of fights, which has happened maybe 3-4 times, paled in comparison to our last one.
I told her a week before hand that I was going drinking with friends, then reminded her in the coming days. She at tose times, had no problem with it. Then the minute i went to leave, she said she didnt want me to go, etc etc. Well, i did go, seeing how she slammed the door on me, sent me txts that I may cheat on her, etc, saddened me. After getting home, and sleeping for a few hours, she yells at me, saying why did I do this, saying I dont love her, that we shouldnt have moved in together, and basically, almost breaking up with me right then and there. She even told me a day later that she almost did. Well, not long later that day, she apologized and said she wouldnt overreact like that before. My problem with that is, thats what she says every single time, that she wont do it again yet she does. I love her to death, but im afraid that these kinds of problems/fights will make me unable to continue to make her happy. Not to mention her ideas of marriage within the next 2 years is something I am worried she would try and rush me into.

Summary: I love my girlfriend (of 1 year + months) very much, but am afraid that her being a bit controlling/overreacting wont stop, as she has multiple times said she would but to no avail. I have gotten random thoughts of whether I’d be happier seperating or we’d both be better off in the long run by breaking up and being friends. It just makes me wonder, that when sometimes I dont mind her going to work so I can do other things, or her overreacting, and me getting these kind of thoughts makes me wonder what to do.

[u]My Question: Are my thoughts of breaking up justified, even when I dont have a lot of reasons for it??[/u]

-keep in mind this was both our very first relationship, and that we are both 19 (me) and 18 (her)

Thank You.