hi there, the slow rate of urine flow could be due to the bladder getting compressed by the growing uterus.Any pressure on the bladder or on the ureter
can also lead to the pain that you have been experiencing. It would be advisable to get an ultrasound
done to rule out any residual urine in the bladder post voiding and also to rule out any back pressure hydronephrosis
which could be quite dangerous in later pregnancy
.You could speak with your attending obstetriatian and get it ruled out. Take care.