Allright Kayleigh... let's say you're a crappy grilfriend, since you insist upon it.
Secondly, let's infer that the behaviours you dislike can be changed. What you describe sounds a lot like me a few years ago, and some of those behaviours still rear their ugly heads from time to time. But as a lot of these people have told you, recognizing the behaviours you dislike is the first step to making a change. I think this is called "Self Actualization", but don't quote me on that.
Do you look to others often, especially your boyfriend, for positive reinforcement, instead of relying on your self for it? Is he a crutch for your self esteem? It can be fixed!
So when I realized that my whining was out of hand and starting to get sickening, I knew I had to do something. This is probably about where you're at right now. One thing that my counselor taught me (and this is the only thing I learned from that one :P) is that your "Self-Talk" spawns these complaints through your focus on negativity. Self-Talk is all the messages you are giving your self throughout the day, consciously or unconsciously. Especially during depression, when constant aches and pains are amplified, so are our negative thoughts. And so we are thinking, and then telling everyone about how our back is SOO sore or we are SOO tired... twenty times a day.
HOW TO CHANGE IT: Change your self-talk. This sounds so simple it's ridiculous. But breaking the pattern takes EFFORT. It basically comes down to good, old-fashioned practice. When you hear a negative thought in your head, instead of saying it out loud, think of a positive thing instead. What ever it may be. For instance, if you're about to blurt out for the twenty-fifth time today, "I'm SOOOO tired." think of one good thing about your day. I don't care how hard it is there has to be something. Like "My bus was on time," or "my lunch was good," or "I'm glad to be warm," or "What a pretty sky." It is especially helpful to think of good things about your SELF. And no matter what you think, there are good things. If you really want to work at this, you're going to have to find some things you like about your self, and make sure you tell your self about them often . Even something as simple as "I am good at this" or "I got my homework done on time" or "I am a kind person" or "I am a caring person" or "I have beautiful toenails." Even focus on acheivements, no matter how small, such as "I got up on time today," or "I wrote a good story," or "When I was nine I skipped a rock 19 times." With practice, your complaints will disappear. I know this works because I did it in a few months and ended up being the least-complaining person I knew.
So, to reiterate; Once you are able to rely on your SELF for positive reinforcement of your self-esteem, you will need to rely on others much less for it, which will no doubt lighten their load and help to convince you that you are both a good person and a good girlfriend.
NO ONE on this site believes that you are a horrible person, nor the worst girlfriend in the world. But it's what YOU think that matters, isn't it.
Keep posting.