pregnant? miscarriage?

for a few days I have been suspecting I'm pregnant. I had veins in my breasts, they were very tender and full, and my nipples were wet and leaking at times. today I feel pretty nauseous too. but earlier today I passed a 2.5cm clot that was mostly soft with one harder section in it. i feel really sad that this might be a miscarriage. i took a test two days ago that was negative but my period wasn't due yet so I don't know if it was just too early.