You sound in proportion for someone who is only 5ft. Big boobs would probably look all wrong on you. In fact, you'd just look fat. Girls who are small and slim can look pretty and feminine without even trying, whether they have curves or not, so think of yourself as lucky.
If it bothers you, why not get a book on how to dress, such as the one by Trinny and Susannah, or something similar. It shows you how to make the most of what you do have, and how to dress to show off your best features and disguise your not so good features. You'll be able to see which clothes to avoid, because they'll make you look even shorter and less curvy, and which clothes will maximise your potential. Everyone can look nice, and I think sometimes it's easier for smaller women.
As for what guys will think, don't worry about it one bit! Men like their women to be all different shapes and sizes. There are a lot of men who like women to be small and dainty so they can feel all big and manly next to her! And if a guy isn't particularly tall himself, he'll probably want a small girl, as most guys wouldn't want their girlfriend to be bigger than them. Of course some men won't fancy you, and they might like really tall women, or women with big boobs, or something you haven't got, but you can't win 'em all! All you can really do is dress to boost your self-confidence and be happy with what you've got. I don't think you have anything to worry about though. Just think of all the other things you could have wrong with you, which would be so much worse!