Sometimes I find them hard to retain and it is always a challenge to pee while you're using an enema but you will get used to it after a while. I agree with qunicy, it sounds like you're doing well, you just need to figure out what works for you.
I tilt the bottle and squeeze it until liquid comes out. When I insert them, I usually only squeeze about
85% in so the little drops that goes in the sink aren't a big deal. I have cramping from the enemas sometimes but the more you heal, the less cramping you will have. I do have cramping now if I use an enema even though I am feeling well but I think it's when I use the enema and my bowel isn't 100% empty. On those days, I personally use a suppository because an enema can be uncomfortable.
I notice if I can make it through the 5 minutes of cramps, I can retain the enema all night. It gets easier, don't worry.
If you're not seeing any improvement with Rowasa, you could also try using cortifoam enemas at night. I think those helped me pull through when I was flaring badly.