You need to work on ways to convince yourself that the reality you believe, that you are nervous around girls and not good at dating, is only that reality because you think it so. You are creating fear which is harming you in so many ways.
There are many ways to turn it around to have a more positive outlook towards dating. I could name a few but I don't want to suggest something that wouldn't be fitting for you. Whatever you need to fix it will come to you as you seek out a solution.
It sounds like you are gaining the positive outlook that will help you with your health issues as well.
Do not put pressure on yourself on these dates or self-judge - don't have any expectations.
Sounds even like you are beating yourself up for not knowing what you want. What you need or want will come when you are not looking for it.
Just get to a state where you can enjoy the journey and appreciate the health issues as a reason to help along the journey.