I also have trouble with this and have had small flow since being diagnosed with MG. Some things that have helped me include pelvic floor therapy and using straight catheters. I also did a urodynamics study which revealed that it was a neurogenic issue. I did try a supplement called urikind (which is not available in the US). I was also told that most of the medicines are typically for men and not women. So, there wasn't any medicine that I could take to help. A couple doctors suggested a sacral nerve stimulator, but this is something I still need to talk to my neurologist about to see if its safe with MG