I can definitely say you're in the middle of what I coined last year as "an emotional [censored]-storm"! It's an awful place to be...but you know what if you didn't love him, he couldn't hurt you this way. Love can make you feel awful, just as it can lift you up.
Here's something I do when I'm feeling dumpy (as you seem to)...make extra effort on your appearrance. I'm no supermodel myself. I weigh more right now than I have anytime in my entire life, and I HATE that. But just because I weigh more and am depressed about that is no reason for me to neglect my appearrance. No matter what I need to take care of myself. It's really important for you to recognize that YOU are worth the effort.
No matter what else is going on in your life, do your absolute best to put your best foot forward EVERYDAY! Walk out that door and be gorgeous woman that you are, size 18 and all! I'm telling you it makes a difference...I get approving looks from men everyday who are appreciative of my appearrance.
And.....if you take that extra effort on yourself everyday, you're bf is likely to wonder what's up...and start taking notice.