Could I Be Pregnant?

Me and my husband have been TTC for about 4 months now. I have been tracking my cycle, and especially my CM. My cycle is 28 days and I started my period on August 7th. Thing is, when I was supposed to start my next period (Sept 5th) I wasn't bleeding like normal, it was more like a medium spotting that only lasted a few days. I usually get cramps a day before I start and the day of, which would mean the 4th and 5th, but didn't get any till the 6th, and as fast as they came they went. I haven't had any trademark symptoms ( tenderness, food cravings or aversions) just a little bit of nausea I've been experiencing for about a week. Biggest thing is that I have no sticky stretchy egg white CM, like I should have gotten about 3 days ago. Could I be PG? I took a HPT on Sept 2 and again on the 4th and it was (-). Thanks!