Until you can get cranberry pills, just drink as much water as you can to try and flush it out. I also recommend that you get cranberry pills, you can natural ones, I think the most common brand is AZO, instead of cranberry juice. You have to drink A LOT of juice to get the same effect as 2-3 pills. I'm one of those "lucky" gals that gets UTIs a lot, so I keep AZO cranberry pills handy. You should be able to get them at the grocery store near where you would get monistat, etc. Good luck and also it is worth talking to your OB or MW...letting a UTI go untreated can be dangerous if it travels to your kidneys! I don't want to scare you, but just want you to take care of yourself and your LO!
I second flushing with lots of water until you can get out and pick up some supplements. And avoiding all sugars and refined carbs so that the bacteria doesn't have more to thrive on. Once you are able to get out or if it is easier to order online I recommend Cranactin capsules. I have GREAT results and have never needed the abx if I caught it early. I do 2 a couple times a day and feel relief very shortly. I get them for a really good price on vitacost.com and they offer rush shipping for a little more $. D-Mannose is good as well. I have not researched it in pregnancy either but used it postpartum often when I felt ran down. I hope you get some relief soon!