Hi JH, great pointers from other posters. I am no expert but when I was younger I also experienced this kind of social anxiety. I actually think it's a lot more common than you realise and many people feel this way at some point.

I would like to say that you seem to be beating yourself up that you got nervous in this initial conversation and interpreting it as meaning you won't be able to develop relationships. Actually the initial conversation such as you had is often the most nerve wracking as you experienced, because you don't know the other person and it is taking a chance. You did the hardest part - well done!

I think experience builds confidence, so the more casual conversations you can have the better, you can practice with just about anyone, you may well find it easier with people you are not romantically interested in. Build your confidence slowly and in steps and try not to tear yourself down - be patient. Good luck!