Is it medication for anxiety? What are you taking?
You do need to discuss it with your doc and think about it a lot. Only you know what's right for you.
But in my personal experience I once took a medication prescribed for anxiety, and same as you said it made me into a zombie. It was horrid, but I guess right at that moment I was fine with being a zombie. This was in Spain by the way, and by the time I got back to England I knew I hated that medication. Unless you're recovering from a trauma and just for a while NEED to not feel anything I think being a zombie is the last thing you need in life. It's not a life, is it?
I got back anyway and told my doc what I was on and he was like "woah" (ok so my doc didn't really say woah lol)... he said that they don't even prescribe it in Britain, that Spain is crazy with some of the things they prescribe. They also prescribe it in the US though.
I think sometimes some meds can do more harm than good.

If you're on meds for your bipolar it's prob recommended you keep doing so, to keep it under control. But if it's for the anxiety I'm not so sure, it's a good idea to talk to your doc about what the med is really doing for you.

But also.. don't let your father in law tell you that you're fine when you're not. You know yourself more than him. He's probably trying to help, but telling you that you don't need meds is a bit irresponsible cos they could be what's holding you together. So yeah... talk to doc if you're concerned.

And lastly well done for going and going to the festival too!!! Anxiety is horrid, but I do think to an extent it can be overcome by just doing things anyway... it's so great you 'felt the fear and did it anyway'. You should feel proud of yourself.