This sounds like more than hormones. You should definitely talk to someone about it, and get therapy (or even medications if it's truly terrible, although meds are usually not as good of an idea for someone so young). Can you talk to your parents about it? If you can, ask them if you can see a therapist of some sort. Does your school have a counselor, psychologist, social worker, or guidance counselor? If they do, ask to speak to that person and describe how you feel. At your age, your school is probably the most accessible form of help apart from your parents.
Hello. I am sorry you are feeling this way. I can relate very much, as i too began feeling very down at 13. I would as you say, feel like crying alot or all the time, and i have infact self harmed once.
But listen i beg of you to not start that, as for some it can become an addiction. Pkease dont destroy your body, i hope you can find another way, if you ever have an urge to self harm, find another way which wont permanantly damage your skin.
Also depending on your life circumstance at the moment, it may not ONLY be "becoming a teenager", and the hormone changes that come with that.
Maybe you may want to talk to someone. if there is something bad going on in your lofe at the moment, then that should do you some good.
Good luck. We are here for you. :)