He won’t make it official ...

I’ve been with this boy for 10 months, I’m 16 years old and I lost my virginity to him, we act as if we are a couple and do all couple things, he’s loyal and a lovely boy and I know he’s not seeing anyone else. I really love him and I can’t imagine my life without him. However in September he ended it with me because he wanted to focus on doing well with work etc, I was distraught to loose my best friend and also the boy ive thought would be my boyfriend. He reminded me it was nothing to do with me and that it was because he just can’t commit to anything atm, but I can’t help but think it’s because I’m not skinny?? Since we’ve been broken up I’ve still seen him a lot and had sex with him many times. I just want him back 😞 opinions?? Is it me?? If he really loved me he would be my boyfriend right?? Xx