I know I'm closer to my goal weight than you, but I've lost some weight since I got with my boyfriend and... insecurities feel awful whatever size you are, so I know how you feel and hopefully I can help.
I've been with my first proper boyfriend for about 5 months now. I know how you feel, I was very nervous when we first got together. No guy had ever seen "mah goods" before because I'd been too insecure about how I look. But my gorgeous flatmate and best friend of a year and a half, who I secretly fancied the pants off of, turned to me in February and told me that HE liked ME! And he had for a while! WHAT! But after the first "woooooooo" I realised that this meant that he had to see me nekked.
And this was half way through the year, I'd put on some weight and it felt like the worst time body-wise for him to see me. I felt the same as you. I'd seen the girls he'd talked to on nights out and they were so skinny and his ex girlfriend had a ridonkulous figure, and he himself is lean. He's the kind of boy that accidentally loses weight. (The only thing I hate about him)
I even spoke to a friend about it, because I was worried about what he might think. I feel like I'm very good at dressing to disguise my problem areas, and I've hated my big (saggy) boobs for as long as I can remember, so I was so worried he'd be surprised and disappointed when things got intimate. But what she said assured me, so I hope it does the same to you: He already likes you! He knows what you look like, he's DEFINITELY checked you out, even if you haven't caught him looking. And he's gonna be too busy being self conscious about himself to criticise you.
And although I still find myself covering up a bit, or telling him off for looking at me when i'm getting dressed, I realise that he's only looking cause he fancies the pants off of me too.
And... he loves my boobs! I think he thinks they're my best feature!! I'm not sure I agree with him, but I've never felt better about them. He's really boosted my confidence, and I think your new fancy man will too. And a male friend once told me after I moaned about my stomach: if you've got boobs and a bum they're not going to be looking else where. And I think that's true. :P
And in reference to the "him being lighter than you" thing (wow this is a long comment I'm sorry)... he probably likes that you're curvy. That's probably why he is going out with you! My sister is very curvy and yea, overweight, and her boyfriend is stick thin... and he loves her curves. He hates skinny girls, and he's desperately trying to put on weight. So he might think this is his problem rather than yours! So don't worry too much about that.
So try to be confident, feel sexy, cause then you'll look sexy. And definitely don't point out anything you're insecure about, because that will make you feel 100% worse. He's my best friend, and I love him, but I still don't talk to him about my doughy belly or my saggy boobs.