It will get easier...When I first started venturing out 20 min was my limit too before the balance problems and overwhelming visual and auditory stimulation started. (earplugs are a must) I started with leaving an event early then progressed to leaving for a short break and coming back to it and now I can manage a couple hours - for me, this has taken 2 years to accomplish - so think baby steps...

I still get balance problems early on but I have learned that in my case they don't progress and I just have to be careful not to turn too quickly - haven't fallen over yet. Also, don't overdo the social chat as I still find that making conversation is a big energy drainer. Pick your moments and just enjoy the fact that you are out and about again!