I'm the same, just started trying or more like just started not using contraception I've been surprised how scared I felt as I've always wanted DC but now keep thinking of all the holidays we won't get to go on! Silly I know!
PCOS is all the more reason to have regular sex. I have PCOS too and have been trying for 3 years now, but don't panic it doesn't take everyone with PCOS that long!
The reason they say 3 times a week is because the egg will only live for an absolutemaximum of 48 hours after ovulation, but it is more like 18-24 hours. If you do not have sperm in your tubes waiting for the egg in that small window then your chances of getting pregnant are slim. Sperm can live for up to 5 days, so that gives you more of a chance to get the timing right, but remember that it can take them a good 8 hours to swim up to meet the egg, so you have your best chance if you have sex in the 24-48 hours before ovulation takes place.
You need to get to know your cycle, though I know how hard this can be with PCOS. Spend a few cycles making notes about how you feel/any signs so that you get to know what your body does in the run up to ovulation. Some women get lots of cervical mucus, some get headaches, some get backache, etc. It will all help!
One of my main symptoms is crippling ovulation pain which I think is because the cysts on my ovaries get so large. Add that to the painful 2 week periods and all the other lovely symptoms and I'm really not looking foward to coming off the pill. Its taken me about 4 years to get on top of it and now I'm going to upset it all again - I must be insane
I also have PCOS and i was trying to get pregnant for a year(!!) until I realized I didn't ovulate at all...i started tracking my cycles and noticed that there was something wrong with my cyles, then visited a good doctor and after few month i got pregnant with my first son! now trying for another one, and no results so far.