If you've always been irregular then chances are you still will be even after coming off BC. I'm not sure about the spotting though. I don't remember if I was irregular or not, but I do know that I had longer cycles before BC. I was on BC for about 9 years straight, went off and got pregnant on my second cycle.... everybody is different.
I don't know about the spotting part. But I was on bc for a year then I got off and tried to concieve with my daughter that I just had. It took me a year to get pregnant with her. Just hang in there and be patient. They say that the longer that you're on bc could be a longer wait to ttc. Good luck and keep us posted!
brown spotting is common in some women, i get it up to 5 days before AF is due, some women get it and it could be a sign of implantation. i've been ttc for 19 months with no luck so far as far as i am aware i don't have any problems my partner will be tested end of July. Just keep doing what your doing with charting ovulation and body temps. I hope you get the results your looking for