I don't know what's going on with my period!

So I had the Marina in for 5 years. I got it takes out January of 2015 and got married in October 2015. Since our wedding we have been ttc. My period has been mostly regular since I got my Marina taken out some months it's 2 or 3 days at the most late. Last month I used strips to see when I am ovulating got a positive result so we tried. My period was due July 10th Monday I had a little brown Okay so I should wake up and have it. That's how it usually goes but the brown continued for 2 or 3 days the last day I had a little red with alot of mucus not enough to put a tampon in. I have taken 2 pregnancy tests and both have come back negative.

Has this happen to anyone?

Could I be pregnant? And the test couldn't read it because it's to early?

Any comments appreciated!