I have been on and off with my ex boyfriend for 2 years, and recently he came down for his birthday on the 31st Jan 2016, he stayed until the night of the 5th of Feb. Through the week we was having sex until he left on the night of the 5th of Feb... My last period began I believe between the 20th-25th of Jan and lasted 5 days (as it usually does, and I am usually around the same time every month) For some reason, I felt automatically I was pregnant! so I took a test on the 8th and it was negative... Me and my ex have had a very complicated relationship and long story short I began seeing someone else, sooner than I expected me and this new guy had sex for the first time on the 19th of Feb, and again on the 22nd of Feb. On the night of the 19th of Feb I couldnt sleep properly and felt very sick, I thought this was because I felt guilty because I was with someone else and not my ex who I dont believe I was completely over. I then felt sick on the Saturday night and then the Sunday 21st I felt sick all day, unable to eat properly and even the smell of things was making me feel sick - however, I thought this was due to a mussel I ate on friday night because I couldnt even swallow it because it tasted funny. That week between the 22nd and the 29th I was feeling sick all week, not able to eat many things, and when I did eat I was starving and then felt unbelievably sick! I took a test probably on the 23rd and it was negative again, but i was under the impression it could because it was still kind of before my missed period. On the Saturday the 27th I took two pregnancy tests and it was positive. Now on the 7th of March I have had a scan and they've told me I was about 3 weeks pregnant; and on the scan they said all they could see was the yolk sac. There was a black section and then a tiny spec within that when I saw the scan, and there was no heartbeat or anything yet. 

Basically, I really do not know who the father would be?!  Can anyone help please? And can no one judge me, I didnt plan for things to be this way! Please HELP!