Should I have sex with him?

So I met this guy, Sebastian, when I was 12.5 we were just friends for a few months. A few of our friends accused me of cheating on my boyfriend with Sebastian but I wasn't. They also accused me of cheating with two other guys. I was telling Sebastian how the other guys weren't right for me. & that he was too old for me & he agreed. I really did like him but I told myself no because hes 3.5 years older than me. We were just friends for a couple of months & then I found out I was moving. I told him & he said that he'd do anything for me. I said like what & he said draw you a picture, write you a letter, do a back flip, give you a hug..... a kiss. I was so excited! I picked kiss, obviously. We decided that we would do it the night before I was leaving because we had this lock in at our church so we'd be together all night. I broke up with my boyfriend & really started falling for Sebastian. We'd hang out & flirt but it was really innocent. That night at the lock in he told me that he was a flirt & showed me that he was flirting with 3 other girls. I was so upset & crying but I got over it & kissed him! We didn't make out or anything but it lasted about 8 seconds or so & its the best kiss I've ever had, his lips were so soft. I was almost 13 by then. He was really innocent. I was at my aunts wedding & had a glass of wine & he got mad at me. I made out with this guy I barely knew & let him feel me up & he was worried about me. He never asked me out though. I would tell him I love him & he wouldn't say it back. I eventually got so depressed because I had just moved and had no friends and me and my dad were fighting so I got my cell phone taken so I couldn't talk to my friends & I cut myself. I had cut before, just a little heart on my hip because i was a little depressed but mainly bored. But then I cut my wrists. We didn't talk for a while & then we started talking again & he was really different, he would drink occasionally, smoke weed a lot. He wanted me to have sex with him and I just played along because I wouldn't see him for a while. I totally should have not fallen for him & realized what was going on so I take full responsibility for getting my heart broken. He had sex once but it was out of comfort with a girl that was 5 years older than him. We were talking about it and he said he doesn't want to do that again; he wants to have sex because he really loves someone and/or understands that it cant be too serious. I feel the same way. I'm not super innocent. I've made out with girls and felt them up and I've given a guy a hand job. I have a choice to see him or not next summer. He'll be 18 and I'll be almost 15. He'll have just graduated and I'll be a sophomore. I really want to have sex with him but im insecure about my body. I have a average size butt and I'm athletic but my boobs are only 34A. I'm going to get a boob job at 15.5 but I don't want to lose him! If I wait do you think I will never have the chance to have sex with him again? Do guys care about boob size that much? I'm not getting breast augmentation for any guy, I'm doing it for ME. I'd also like to say that I'm very mature in personality & looks. People always think I'm 2-5 years older than I am. I'm 5'7". So yeah, should I have sex with him? or wait till I'm almost 16? Thank you so much for taking the time to read this! You're a life saver! (((: