Oh and by the way, try not to rely on symptoms as a sign you're pregnant. A lot of the symptoms mimic your period coming, and for many women pregnancy symptoms don't start right away anyways. I always said that I had more symptoms when I thought I was pregnant than when I was actually pregnant. Just wait and keep testing, all you can do.
First response is one of the most sensitive, so I'm not sure what else I'd recommend. I like the digital ones because they give you a definite "pregnant" or "not pregnant" but I did do the first response one first. Just keep in mind even the most sensitive tests might not pick it up before you miss your period, so you probably will just have to be patient, or you'll go broke from all the pregnancy tests you have to buy. :)