I am trying to get pregnant and I had my period dec 4-7 and ever since I got off my peropd I have had unprotected sex and today dec 30 I had brownish stuff then light blood and I put a tampon in because I thought I was going to satrt bleedin and I just went to the bathroom and there was only brownish stuff am I pregnant?

Please understand that we cannot diagnose you over the internet. If we could I would make a million bucks asking girls to pee on their monitors. LOL

It sounds as though you may be beginning your period. Do you have a regular 28 day cycle?

How long have you been trying?

Yes I do have a regular 28 day cycle but if I am getting my period it should come on dha 1st but I been trying since October 1 07

See what happens over the next several days. Cycles can be off a couple days here and there. You would be due at anytime with a 28 day cycle so it could very well be your period getting ready to start as J_9 mentioned.
If no period by next week, try a pregnancy test.