Should I be mad at my mom, or can I just leave the problem?

So lately it's been super duper hot where I live, and I keep asking my mom if I can go to the aquatic center with my friends. She says alright and we'll go after dinner. So I think, sweet! But after dinner, I keep reminding her that I have to go and she tells me to wait 5 more minutes. So by the times she tells me to get in the car, it's already 8:00 pm! I yell at her I never get to see my friends anymore because they are all in band and got to go to San Diego for 2 weeks, and I'm like the only person in my group that doesn't do band. She not only does this with the pool thing, but every time I am ready to go to school, I constantly have to tell my mom to come down so she can drive me. I yell, "It's 8:10!' (School starts at 8:15) She comes down, and says that she'll be right back down once she puts on some facial perfume! What the hell? And trust me, it takes like, literally 3 minutes. I am always late for school and my teachers are always yelling at me! I have even thought about running away from home because everyone in my family treats me like a piece of crap and people at school tease me because I am "overweight." (By like 10 pounds.) So, sorry this is so long but do you think I should be mad at my mom?