i am 5 months pregnant, but my husband and me are not prepared

5 WEEKS SINCE LAST PERIOD. Hi All, I'm in a long distance relationship so only sexually active when we are with each other every 4-6 weeks. The last time we were together was the 2nd-9th April. I then started my period after he left on the 10th April........ I was due my period on the 9th/10th May but have not received anything and it is now the 19th of May! I have done two tests and they are both negative. I am a little confused/concerned as I have always been regular, so this is unlike me. As for symptoms, nothing really.....however I have had the sensation that my period is due, and have done for the last 2 weeks, but every time I check NOTHING, and also quite a large amount of discharge the week I was due. So really I wanted to know: Is it possible to conceive so closely to your period, have your period and still fall pregnant? Secondly, should I do another test? Any common situations or experiences I'd be pleased to hear about them. Many thanks