first of all, there's no specific weight at which you should wear a bikini, if you want to wear a bikini wear one. Drink a lot of water, be careful of what you choose to eat, but don't deprive yourself because you'll end up overeating and you'll be back at square one and just try and get out and have fun. The guy obviously likes you if you two are already friends, I don't think it would much different if you looked any different because he likes hanging out with you.