It's so exciting and wonderful that you are discovering and exploring both within yourself and within your relationship. Sounds like you are really on a roll with digging everything up that could be between you. It can be really scary at first - a lot of that stuff stays in the dark because it has such a potential to hurt. I can almost hear in your voice how eager you are to root it out, to turn it all into something even better. That really respectable, and you should be proud of the progress you have made already. Isn't it nice to know even if nothing more happens on the poly path, you two have already gained valuable insights?
I know everyone has already mentioned the "feeling attractive" issue, but I just couldn't let it lie. What I have seen and learned about it is a little counter-intuitive. I got to suggest it, though - I would hate to see you chasing windmills.
So here it is: the feeling that you are an attractive person is NOT something that somebody else can give you. It doesn't matter how many people want you, it doesn't matter how much makeup you wear, it doesn't matter how heartfelt and plentiful compliments are, hell, it doesn't even matter how you really look! Yes, sometimes those things can provide a temporary burst, almost like a mood, but being and knowing you are attractive comes from within. No one else can give it to you.
They can't convince you. You have to believe it yourself first before you can be receptive to positive reinforcement. It sounds silly, but really, it has VERY LITTLE to do with the outside world.
Well, I hope that helps somehow. Best of luck to you both and keep your faith in your communication!