I think the confidence problems are relatively common. What would help is joining some kind of hobby that can help build up your confidence without making you feel physically worse. This article was a really nice read: Staying Positive with Fibromyalgia Getting out there and participating in what you are still able to do could be a very liberating experience for you.

As for dating, I found this list of sites specifically meant for people who are disabled or looking for a relationship with a disabled person, if you want to take a look. So, you could feel confident sharing yours because it's be expected that you have a disability if you're on the site. Top 10 Dating Sites for Disabled People