Could I be pregnant already?

Had my period 4/11/11, and had my iud removed 4/21/11, and had 4/22, 4/25 and 4/26. The 23rd had some light spotting only for the day. Also, lately been feeling nauseated, bloated, peeing alot and sore , had some mucous like clear slime like discharge, due for my period today or tomorrow but nothing. Took a few tests but all negative. Could I be pregnant and just too early to test? Lots of backache and headaches bad.