I think we've all had a bit of wee at some stage!
It's the weight of bubs on your bladder & your pelvic floor muscles.
You can & should do kegels exercises to strengthen these muscles. You tighten the muscles as if you are holding on - needing to wee - for about 10 seconds I think. Have a 10 second break & do it say 5 or 10 times at a time.
If you are in a city they say to do it every time you see a red light to remember. Or maybe you could do it every time you open your fridge.
The best way to practise is to go to the loo & stop your wee half way through. Thats your pelvic floor muscles stopping it. Thats what the exercises are.

Maybe the vomiting is just coz your belly's a bit shaken up?