12 weeks pregnant with UTI symptoms

Starting on Monday I started experiencing frequent urination. I figure that I'm finally experiencing a pregnancy symptoms since I've had NONE. I'm 12 weeks as of this week. But I knew something was wrong whenthe pee started to sting and there wasn't much coming out. On Wednesday I called my OB and she said to come in to give a urine sample. It came out negative and they said they will send it out for a culture but results won't be back for another 5-7 days. I'm still having these symptoms! I don't know what to do. They won't give me anything or prescribe me anything since it came back negative. They wouldn't even recommend AZO and of course I won't just take it on my own. Any ladies have any advice? What could this be if it came out negative? What can I do to help my discomfort?