anyone having sex, with supposedly "perfect use" of birth control, can become pregnant. period.
hell, my naughty little 5 year old was conceived while we were using birth control and religiously tracking her cycle. "oops" happens.
you have not had "perfect use" of the pill, which increases your chances.
you also cite symptoms which are purely "presumptive"... which means a balding 50 year old male can feel the same symptoms.
so...
the ONLY HONEST answer is NOBODY here can tell you whether you are or are not.
if you are, thats only determined by time and testing... and some womens bodies take more time to build up hormone concentrations.
that said... every med student who ever took a class "self diagnosed" themself into a "disease of the week"...
stress alone (worried about preg) can cause your symptoms.
wish i could tell you definitively "yes" or "no"... absolutely NOBODY worth their weight in knowledge will tell you "yes" or "no" here...
yes... you could be. you had sex. imperfect use of BC increases your odds, but its better than nothing. your "symptoms" are not unique to being pregnant...
so "maybe or maybe not" is as good as its going to get.
now its time and testing...