Missing period because the pill is not out my system or could i be pregnant?

hi! any advise i would really appriciate. i stopped my pill end of march time had a bit of spotting then, here are the dates of my next periods:-
day 1 started bleeding:- 21st april
day 1 started bleeding:- 26th may
day 1 started bleeding:- 29th june
i assumed that my periods were regular after coming off the pill after 7 years because i have had a few normal periods i think they work out at averageing a 35 day cycle, today is day 38 and i have not come on, i did a pregnancy test about two weeks ago just because we are trying and was hopeing to get a possitive but was negative, have not done a pregnancy test since. My stomach is off but i suffer with ibs to so that does not help, i have a poor diet so i have gained weight lately and boobs have got bigger, i do feel sick in the morning and throughout the day, but i just keep thinking is it my ibs or am i going come on.
I know you can miss periods after coming off the pill but after havin a few months of normal periods i thought i was back to normal, could this be the case, the pill is not out my system or could i be pregnant? i normally do a test every other day but i am scared to do one incase i do get a negative as me and my fiance want a baby, please any advice would be great king regards Tina :-)