Am i pregnant ?

ive been on the pill from nov till earli december buh i messed it up lots of times so i gave up n stopped. Then i had a period on 27/11/07 my periods normaly last a week. This meant my followin period shud of came on 25/12/07 id been havin unprotected sum days. i gah sum realli light light bleediin on 20/12/07 which lasted about 2 days if i ovulated on 11 dec and 3 jan is it possible i cud be preg ive been feeling sick eatin n sleepin alot peeing every half hour no energy sore bak im bloated its like a baby bump. i got dark brown bleeding todsay which i think cud of been implantation bleeding ? my next period is due on 16 jan! i tuk a test last thur buh it was neg was i too earli to tell yeh? i have an appointment for the doctors on fri for a blood test what do yall think? could i be preg! xxx i need ansas xx