This Is Driving Me Crazy

Hi all this will be rather a long post sorry if I go on!

Periods quite regular ( 30 days ) they last approx 5-6 days. I am on lustral for panic attacks recentley reduced dose by half as I am feeling great ( gps advice )

last period was november 12th normal 5 days

me and my fiance ( getting married in june ) dont use protection as we would like children if it happens it happens due to wedding we are now using the withdrawal method ( I know that this is not safe but we dont have any stds and we want children )

anyway middle of dec my breasts start to really hurt more than normal by 16th dec no period I do a test its nagative wait a few more days no period do another test negative again..... Then on the 20th dec I wipe and there is blood ...Finally I thought I had my period but no it stopped after approx 4 hours.

So until yesterday I felt ok no sickness or anything except heartburn and a bloated feeling and a dragging in the bottom of my stomach but I put that down to my tablets and reducing the dose..... But I went to the toilet this morning I wiped brown discharge this time for 2 hours now nothing.

I am very overweight and my stomach is feeling bloated .....Although I have done tests and they are negative could I be pregnant?

I know that I dont have any stds and my recent smear/pap was fine......But I am worried.

What can this be?

Thanks hayl