Delay in menstrual cycle. Pregnant?

Hello,I am 33 year old and I am married from last 11 months.This month my periods are delayed for 15 days as of now.I had got my last period on Feb 8, so expected next periods on March 7th but till now I didn't get it.Does that mean I'm pregnant? I tested on 8th day after I missed my periods but the result was negative. The duration from Jan month period to Feb month was 25 days. Before that I had irregular periods for 3 months and each time I was getting period within 20 days of gap.I had consulted doctor and was under some medication. I suppose it was period correction medicine as I have told doctor that I wanted to conceive desperately. After that medication my periods was ok n I had got on 28th from the previous month. Note:The last intercourse I had with my husband was on 10th after my periods were completed in Feb.After this we never had intercouse. And now my periods are skipped. Are there any changes of me being pregnant?I am having stomach ache from past 7-8 days.Pls suggest.