I have the exact symptoms after a BM... I am 42, 2 children, and have had this weird thing happening for over a year. Pap is great, but I do have a small cyct on my ovary, just found 5 weeks ago. Now the plan is they do another ultra sound of my "girl junk" and then see if it is getting bigger. Dr. says its non-cancerous, and does not think the bleeding is related to it, but I find that hard to believe! I thought about trying an IUD but wonder if that is wise with spotting, as well as occassional migraines. If you find out what is causing the bright spotting with bearing down please let me know, the Dr. did not think the cyct was the cause.
Pap smears only test for cervical cancer. One thing you might ask to be checked for is ovarian cysts - which would not be detected durign a pap smear. Cysts may be able to be detected by a pelvic exam, but only if somewhat large. A better method (though costly) is to have an ultrasound done of your ovaries and uterus. 99% of ovarian cysts are benign, but they do need monitoring. One common symptom of cysts is unusual bleeding, so it might be worth looking in to.