my period is now 13 days late

Am I pregnant???
After reading all the posts it seems like a lot of woman experience the same thing!

I am always regular with my period, every 28 days to be excat.
The problem is, that my period is now 13 days late.
I am experiencing swollen breasts, larger nipples, a white discharge with no smell, frequent urination, and this strange taste in my mouth; all of which are signs of pregnancy.
I have had 5 pregnancy tests, the 2nd to last one yesterday was a different brand from the rest and has a negative line and a very faint positive line. But the one I did this morning is negative again.
I have had one blood test and that was negative too.

I am very confused and anxious.

I've never been pregnant before, but I feel pregnant.

Any advice or information would be appreciated.

Thanks.