PMS symptoms yet no period ?

so, i've got an irregular menstrual cycle (sometimes i go 18 days, and sometimes as many as 40.) but one thing that stays the same are my PMS symptoms. i usually have sore/lumpy breasts, a dull backache, bloating, and irritability for about 3-4 days, and then get my period flow. however, it's been almost a week of sore breasts and irritability - yet no sign of my period. it's been 22 days since my last cycle.

i did have a pregnancy scare, but i don't know if i should still worry. the sex was protected and happened about 4 months ago. i've taken 4 pregnancy tests, all of which were negative. i've had 5 periods since then, but they were somewhat lighter/shorter than usual. i also went to my gynecologist about 2 weeks ago. she performed a pelvic exam, and said there were no signs of pregnancy. SO, i'd figure that a pelvic exam almost 4 months after sex would show pregnancy, if it was there. i DON'T think my doctor and 4 hpts could be wrong.

i'm worried that my period's not coming, yet my breasts have been sore and achy. should i just wait to see if it shows up soon? what do you all think?