Finished my first round of clomid!

I just finished my first round of clomid and got a +ovulation test on 9/3-9/5. I went in for my progesterone test on 9/10 my progesterone level was 7.3. She said that was a little lower than they hoped but just wait to see if I start my period and if not by day 42 test an call the office. I took a pregnancy test on Tuesday and it was negative but midday Tuesday when I wiped there was dark brown with discarge on the tp. could that have been implantation bleeding? I'm so confused and anxious! Please help!!