I think that you may be as the dates that you have given, if you have regular periods and regular ovulation dates then the time that you had unprotected sex would have been on your ovualation dates. With the side effects that you have are also a high indication that you could be too.
I came off the pill on 13th May, had period 17th May and made love on my ovulation dates too. I have had swollen breasts and very sore, nausea and stomach cramping, i am due my period on Thursday so just have to see but i really do feel pregnant.
Well all i can say is the only ay you can be sure is to take a pregnancy test. . . the symptoms ur having could be just the fact you know they are what happen when ur pregnant so ur mind makes them real, i had it so much lol. . . . Good luck and i hope the result is what u want xx