I have to catheterize 3* a day to pee but when I'm done I still feel the urge and pressure that I have to go is it possible I'm still retaining fluid?

Possible. If you still feel bladder pressure after self-catheterization, it could be because you have not emptied the bladder completely, although this is unlikely. It could also be because you have a bladder infection or other cause of inflammation. I would get a urinalysis and take it to your doctor to discuss.