I'm 13 weeks pregnant now. Since the beginning I have needed to pee at night, once or twice. The last couple of nights I have woken up about 4am really uncomfortable and bursting to go, but then really struggle to actually pee at all 
Last night was really bad, I was absolutely desperate but couldn't go at all. I started to think actually I didn't need to pee after all and was uncomfortable because of something else, but eventually I managed to pee a little bit standing up in the shower, and then did properly emptied a full bladder's worth on the toilet.
But what on earth is going on? I can go fine in the morning/day time, it's just at night I literally can't squeeze a drop out?