so i think i have a badder infection

here are my symptoms
weeing alot
feeling i need to go again after i have been
sometimes its only a little bit when i go
lower ab pain
back pain
burning stinging pain (inside ) not necessarily when i go

i went to the Dr the other day he wouldnt give me a pee stick test but sent it off to the lab, straight away even without knowing if i have an infection he gave me a script for 'Keflex ' he said i need to take it asap or it could hurt the baby??

Do you think i have an infection? does it sound like i do?
have you taken Keflex? should i go gt it filled now and take it, my results may be back tomorrow not sure.

I read up on this drug and its a cat b drug and immscared to take it , isnt there anything cat A they could give me.

sorry just all scared and dont know what to do lol

thanks