pregnant???

hello,please help me  i had my last period on the 22nd Dec 2011, my cycle is around 31 days, i had unprotected sex on the 7th jan right through to the 13 missing a day in between, i had EWCM  from the 7th for a couple of days and then it didnt dry up and then came back egg white again on the 13th until the 15th,when would i have ovulated??? i have done a few pregnancy tests but they were negative which i assume its because its still very early. i have had a weird taste in my mouth today and small amount of cramping on and off the last few days,i have also had some yellow tinged mucus but its definitely not an infection. i have those Montgomery bump things but i also had them with my 1st and they never went completely away and i havent payed too much attention to them for a while so im not sure if they became raised like they are now when im cold or in the shower  in the past 2 years. please help as its frustrating to play this waiting game and trying to figure out ovulation :(