Got all the symptoms of pregancy but period has come?

About 2 and a half weeks ago i noticed veins in my breasts and they where tender. A few days after this i started noticing bad cramping just like period pains, breasts got sore, going the toilet all of the time even though i am limiting my drinks to just two a day, also had bad constipation, headaches, nausia, the smell of ciggerette smoke, cleaning products and fried food really got to me. I was convinced that i was pregnant so i took a test. Although my period was abserlutly normal last time i thought id check. The test was negative, however it did say that i cannot take it until one day after my period is missed which takes me to today. However, my period has come one day late. I had some spotting yesterday and some yellow discharge before this but this morning i had come on. Its a little heavy and dark coloured and thick. Also clotted a little bit. I took another pregancy test this morning, negative again. I dont understand how i can have all these symptoms iv felt like ive been on a period for the last 3 weeks!!Could i still be pregnant or is there anything else it could be?