your mom wants what is best for you.
and if that seems like its overprotective, its only because a part of her does not want to let her little girl go.
shes not doing this to ruin your life, cause problems or start fights with you, she is just nervous to let a young girl at 15 such as yourself, go out into the dating world, mainly because she does not want to see you get hurt in the end. and i think every parent feels the way your mother does when their children start to hang out with the opposite sex.

the best advice i could give you would be, to ask if you can have this boy come to your house and hang out where she can supervise-not spy- you guys and can see for herself that you are taking this in a responsible manner and not doing god knows what behind her back-not to say that you go wild when she's not looking-
if you suggest this, she might feel that she has a small sense of control, because she will be the one making sure you guys are safe because she has another child in the house-your guy friend-to keep an eye on for his parents, and if she is anything like my mom used to be when i was your age, she might put out things for you two to eat and drink, making sure you guys have a little snack or whatever.
this might break the tension between the whole hanging out with someone of the opposite sex, because again, she can see for herself that you are being responsible and behaving yourself, and she might instill a tiny bit more trust in your hands.
when i was your age, my mom did not like me going to boys houses or boys coming to my house without an adult home, but before i was allowed to boys houses, i brought the boy to my house to meet my mom so she gets a sense of who this boy is what he looks like if hes polite etc.
thats a plus too. and again, its not to ruin your life, your mom wants best. your still young and your mom doesnt want you to get hurt.
try suggesting this and see how things go.

good luck

Hey Ilyblah
You're 15. You're having a difference of opinion about dating with your mom and she's going to win all of those until you're 18 and she's no longer responsible for your actions. If your mom told you that you're not following your agreement with her then that is what she believes. unfortunately there isn't much you can do about it. They are her rules. This is a great time to sit down with your mom and have a rational discussion about how important it is for you both to be on the same page about this. If need be ask her to write down the rules so that both of you are in full agreement and understanding. If you don't like the rules tell her that you aren't comfortable with them but understand that she's in charge. You'd like to add into the rules that you will both sit down in 6 months to re-evaluate how they are working.

When arguing with your parents about being overprotective you never want to loose your cool, whine, make appeals to emotion or criticize your parents, it will only re-enforce their justifications that you are too young to be responsible. If you feel like you're being treated like a child the very best way to fight back is to discuss the matter in a mature, rationional and organized way.