I'm just wondering if it's possible to be asking too many questions. I feel annoying and like a leech for only asking questions. I'm not advanced enough in math to answer most of the questions on this forum.
Correct me if I'm wrong, but I think you're asking not so much about asking loads of questions as you are asking about asking questions but not answering. Is that accurate?
The answer to that question is that it's okay to not answer a lot, or to never answer at all. The goal (well, at least one of the goals) of Stack Exchange is to help people. If you need help on something - not in the homework sense, but in a conceptual way, or something like that - Stack Exchange can be an excellent resource. There are thousands - probably millions - of people like you, who simply use Stack Exchange to learn, not to teach others. That's fine. Sure, it's nice to "give back" (for lack of a better word) to the community, and it can make you feel warm and fuzzy inside, but so should asking questions. That helps just as much. Chances are, others will wonder the same thing you are. By asking, you help provide an answer for them, just by broaching the topic.
This was covered on Meta Stack Exchange, by the way, in Is it considered rude if you only ask Questions but almost never answer one yourself. I'd like to quote Grace Note's answer; it turns out that hers is along the same lines as mine:
I wouldn't say it is bad behavior or rude. You might not be contributing answers to the community, but you are indirectly contributing knowledge (provided your questions actually are getting answers).
Personally, I do my best to see if I can answer questions, but I find an equal amount of satisfaction in asking questions. This is a good place to ask questions, after all.
Oh, and one more thing, on a personal note: I felt the same way as you on Mathematics for quite some time. I'm still not as experienced or knowledgeable as many people here, so I would ask a lot more than I would answer. I eventually started doing some answering, helping where I could. I also began reviewing, when I built up some reputation. I also occasionally suggest edits. Both of these give back or help the community in some way, shape or form.
First, related question here: Is it annoying that I don't answer questions and just ask?
Edit: It appears another user has posted this link already. Sorry!
Second, I want to answer because I want to share my own feelings and experiences on MSE. I felt similarly when I was new on MSE about a year ago. I really struggled in dynamical systems, and would have to bring homework questions to this site about once a week. This was back before the homework tag was removed. I'd say I probably answered a question for every 5-6 that I asked, and I could only answer really simple arithmetic questions or calculus questions, because anything with a different tag was really advanced. I noticed that there were two kinds of questions - low level questions which are pretty clear if you know the material, and a more sohisticated kind of question which is much harder and requires a serious answer after a lot of thought. I felt bad because I thought all my questions were of the first type, and thought people would recognize my name and think my questions aren't worth answering.
So I decided at that point that by asking MSE for help with homework, although sometimes I could get a good discussion going and round out my understanding, I wasn't doing myself the same kind of justice that I would be if I went to office hours and worked with friends in person. I decided that I would only ask questions of the latter type on MSE, or maybe a supplementary exercise to a course if I was really stuck on it. In particular, I wanted to answer a question for every question I asked whenever possible so I could feel like I contributed.
Doing all of this has really helped my mathematical ability in the same way my tutoring job has, and has exposed me to the MSE community in much more detail (plus I get to be proud of my reputation score over my classmates, who just ask).
Another thing I've noticed is that even when I browse questions in categories I consider myself reasonably good in outside calculus, like say, abstract algebra, I still can't always answer most questions. It takes me a long time to come up with the answers and someone beats me to the punch. But I get to sit and think about an interesting question and maybe contribute to solving the problem sometimes. In particular, I feel like his helps me become better at problem solving, and makes working on subsequent problems on this site just a little bit easier.
Now none of this is to say that MSE is a bad place to ask low-level or even homework based questions. Quite the contrary. It's just that by trying to write up homework questions, displaying my work (even when the homework tag still existed I felt inclined to do so so that others would know I tried and wasn't mooching), I was learning what makes a good mathematical question in itself. And this is what motivated me to focus on being a more helpful member of the community.
So I guess what I'm saying is, ask away, and do your best to answer your own questions and other people's. I'm no problem-whiz yet, but by trying to help out here I have noticed an improvement in myself.