Think I might be pregnant right after miscarriage! Advice please!

I started to bleed 11/11 and passed baby 11/12 stopped bleeding by 11/15. Didn't go back for levels check until 11/26 and negative. I had unprotected sex 11/25, 12/5, and 12/10. On 12/10 I had spotting that was bright red like going to start my period but it turned brown and only lasted about an hour max. I've had sore breasts for over a week now and started getting nauseous a few days ago. I tested today and negative with first morning pee. Am I testing too early? Or am I just hoping for something that won't happen? Any advice? Also, has this happen to anyone?