What do I do?

I get really mad at my mom sometimes. Like today, my friend came over since she had to borrow a cup of baking soda, since they were baking cookies. They're more family friends, so we visit each other alot. She invited me to come over there too, and I got all ready and stuff, cleaned my room, took a shower, and i've been doing lots of things like helping with my baby brother, and stuff like that. Then I asked my mom if I could go to their house after doing all that and she said "NO"! I'm freakin' 13 years old, in a nice suburban neighborhood where nothing bad ever happens. It's daytime and people are outside mowing their lawns, walking their dogs, riding their bikes, normal stuff like that. And my mom still says "NO"! Alot of times when I wanna go over there, she says "no" and i ask why and she never tells me why! shes sleeping right now since she works at night. before she asked like what if something bad happened to me.. what the heck? ive been allowed to go all around my neighborhood since i was like 8 years old, but it feels like now that im 13, she has to be more protective over me? what the heck? i tried everything and she was really mad at me when i kept asking her to go. i hate this she never explains why! also for sleepovers its the same. she thinks "something will happen to me". i mean im not retarded, something could, but i dont want to waste my whole childhood without going to one of my friend's sleepovers (she doesnt want one at our house either, cause she doesnt want responsibility over other peoples kids.. i mean its not like we're gonna go burn the house down!) but shes like "no, cuz its her african custom". my dad says the same too. its soo retarded. i mean we can only sleep over at family's houses so thats not really like a sleepover im thinking of. anyway, on the subject how can i get her to trust me more? im a smart girl and my friend lives near, in my neighborhood, like 3 minutes away from my house by foot, about. and i really wanted to help them make the cookies.. geeeez. lots of kids my age visit their friends all the time but my mom just wants to confine us in our house alot!! i hate that. i barely ever get to visit my friends or go out with them to places like the movies, bowling, the mall, etc. UGHHH i cant even go on vacations on them, or to theme parks with them and their family! i mean family is good too but im just really really pissed right now cause im freaking bored.