Hi Youkai,
First of all, welcome to SoulCysters and good luck to you as you come to terms with your diagnosis.
Dealing with body image is a long hard road. My DW and I have been married for 4 years, but have known each other for just about 10 and it's still an issue. As your weight might fluctuate so do your feelings of self-esteem. At some point you will have to come to trust that your BF really means what he says and make a leap of faith, take a chance. It is really the only way you are going to make progress.
This does not mean that you should wait for your boyfriend at home and greet him wearing only plastic wrap or something.
Take it slow. Do what's comfortable. Talk with him about your feelings as you're taking the step whatever small step that might be. Ask for his continued support if you decide to stop shaving the extra hair or pursue other hair removal techniques.
The worst thing you can do is not talk about it. To continue to repress your feelings will only make you feel worse and you've already said you ready to get over that. Good luck.