I'm having this exact same problem, and I understand exactly what you mean about being nervous. I have anxiety over this a lot. I'm about 85lbs overweight currently, and although I've shared pictures with my long distance boyfriend, I'm not sure if he knows I'm overweight, because I look only a bit chubby from mid-waist up and that's what I sent
But, I was also much heavier before then.
However, we've been dating for almost three years, and he's obviously in shape. He was also the one who suggested meeting.
I'd like to think that if he wants to meet that he must like you for your personality at least enough to give it a go no matter your weight if he's the one that suggested meeting. I still have 3 and a half months to lose weight before he can even consider coming to America because he has school, so I'm trying to lose as much as possible before then. And if it doesn't work, it just doesn't (even if it hurts). This is what I tell myself, but truthfully my anxiety still comes back about it.
As for confidence, even if you are losing slowly, you should exercise when you feel nervous. Personally, I always feel really good about myself after I exercise. I'd rather be tone and fat then just flabbily skinny when I meet someone. What's sexier than big, toned thighs?
Also if it worries you too much, you can always talk to him about it; Vaguely steer the conversation with him to health and see what he thinks. That might give you an idea of what to expect;
He might not care about your weight since you're trying to be healthy. That shows you have effort, dedication, and self-appreciation--such positive traits. And if he suddenly doesn't want you because you're a little overweight, then he's shallow anyway, and it's probably for the best.
Also wear things that take attention from your stomach and flatter your good areas, you know the ones.