8 days late!!

My husband and I have been TTC for only a couple months. This is our first time actively trying. We have a 6 year old girl who was a surprise and I didn't find out I was pregnant with her until I was about 9-10 weeks along.

I am 8 days past my expected period and I have had pretty regular periods (+/- 2 days here and there). I have been fatigued and have tender and sore breasts. Light uterine cramping and lower back pain for about two weeks. My problem is... I can't get a positive result. I've taken probably 6 hpt and all come back negative. Is it just too soon to tell? Or do I want this so bad that I am phyching myself into thinking I'm pregnant, when I'm actually not? Advise ladies??