you are probably in danger of getting a kidney infection. Letting the pee back up like that, no healthy. Just go for goodness sake that's what the toilets at work are there for, right. It's not like you are the only person in the world who pee or the other.
I used to stress over the same thing as well. If the seat is unclean use a seat cover or clean the seat with a wet paper towel or something. As for going #2 i'm lucky as we have single room toilets so i free to go and pity anyone that goes in after me although it's not like they will know it was me. It's a natural function, we all do it so why be uncomfortable. Just go!!!!