help! bladder issuea

Hi. Im 17 weeks pregnant. 4th baby. 7th pregnancy. I have had what i thought was a uti for the last 4 weeks, however sample keeps coming back clear and antibiotics i was prescribed and took did not work. Ive now bn taking cranny cleanse in the hope it may be cystitis. But this is not helping either. I am susceptible to uti's but never for this long. Ive also now had swabs for thrush but that doesnt look like the culprit either. Docs again today for yet anotherv urine test and bloods and my gp mentions maybe fibroids or cysts???Now getting a little worried. 18 week scan nxt week so i guess theyll be looking for other lumps n bumps aswell. Most days i have the dull ache and heavy pressure on both bladder and bowel. The feeling of needing to pee and generally looking like crap and being very tired still. This is the saddest 2nd tri ive ever had. Can anyone offer any advice or similar experiences please??????