My Boyfriend Wants Me To Lose Weight.?

First off, I am not fat. I wouldn’t use this word to describe anyone of my size. I am 5’4.5″, 130 lbs, and a size 4-6. I’m not skinny, that’s for sure, but I believe I am a healthy, average, normal, American Caucasian, 19 year old girl.
I don’t over eat, I don’t eat much meat, dairy, or white carbs. I don’t indulge myself in junk food, but I do enjoy a sweet every now and then.
I admit I could be a lot more active, but I wouldn’t say I am a completely lazy and sits on my *** all day. I am usually out and about doing something.
I do enjoy tennis, swimming, bike riding, etc… but getting up for a run every morning or reps just ins’t my cup of tea.
I used to be extremely skinny while growing up. People used to call me peanut, bean, stringbean, toothpick, etc. They told me I needed to put some muscle on my bones. It all changed when I turned 16, went on birth control, and well…. grew up.
My boyfriend of 6 months, is 24, Chinese(I find this important to point out, because it is common knowledge, that asians tend to be leaner), and in decent shape. He works out when he finds time, and really cares a lot about his physical appearance and health. He doesn’t however have the healthiest diet, but he also doesn’t pig out(non-asian cuisine).
When I met him I was the same size I am now. Less than 2 months into the relationship he started making comments about my weight, that made me feel really insecure about myself. He never went about it the right way, and always ended up digging himself a bigger ditch. He insists he finds me sexy, but tells me if I lost weight, our sex life would improve(it is however… amazing). He complains that I am lazy and doesn’t understand why I wouldn’t want to change for him if I liked him so much. I know guys are very visual, but I am not any different from when he met me. If he preferred skinnier girls, why didn’t he go for them?
I’m not saying I won’t lose weight, and I’m not saying he is completely wrong for wanting me at my best… but he makes me feel like a fat ugly loser. Sometimes to the point where I actually cry, but he doesn’t even see what’s wrong. If I want to lose weight, I want to do it for myself, not him. I like the way I am now, and I don’t want him to pressure me so much to be smaller.
How should I confront him with my feelings? He doesn’t understand me when I say “I want to change for myself, not you”.