Well I can help you with this completely.
I skated for over 10 years. My parents too wanted me to wear a helmet, and guess what at first I really didn't like it either, and I too got made fun of. However I didn't have to wear it while going to school or going skate. I just had to wear it at the park. My life was saved over 15 times because they made me wear a helmet, and even after I grown up, and was able to make my own choice3s I continued to wear a helmet. To the fucks that make fun of you, just tell them to fuck off. It's better to sport a helmet than possibly be retarded for the rest of your life with just one fall. Trust me its the right thing to do, and you will get used to it. Just get yourself a nice helmet, and put some sick stickers all over it, and its all good. I once even got jumped by I believe it was 3 Mexicans maybe 4, and I took my helmet off, and beat the shit out them. So it can be used for numerous things. You can also stash stuff in it. What I wold do is tell your parents to allow you to goto school without it, and goring to and from places without it, and agree that you will wear it while skating at parks, or doing big street tricks such as big stairs or gaps. I also won many contests, and had full sponsorship's. Let me know if you want me to answer any questions regarding this or anything at all. Because this is seriously something I know alot about, and I do mean alot!