STD scared

Ok ladies sooooooooo I had a iud in a couple months ago and since then had it removed but when it was in I slept with an old fling. That was back in October. Everything have been fine and I haven't had unproctectes sex since then, but I also haven't been tested (I am on Friday) but lately it's when I pee it hasn't been painful or burning but it just isn't coming out. This could be a uti I know. Well today after I got out of the shower it did burn a bit. So I went to cvs and got a uti tester kit. It came back negative. So like anyone else I went and looked up symptoms of STDs and of course I'm not freaking out.