I hope you can do some more, get a few under your belt and you will have the bug. You do get used to the bad feeling and learn how to suppress it after a while. I have done a few large one's solo, but I can only do around an hour and then have to leave.
If there are others in there, I assume they are other explorers. It is getting very popular over here.
It was definitely an interesting experience for me. Maybe I will give it another shot when I get a chance. I am sure there are sites even much more scary than this one. You have probably visited such urbex places yourself... Anyway, thanks for your encouraging words and support :)