Welcome to MDC!! You have definitely come to the right place for support and advice! I'm sorry you've been having a frustrating time.
First here is a thread about diagnosing PCOS: http://www.mothering.com/community/forum/thread/1313394/do-i-really-have-pcos. Take a look and see if you have any of factors mentioned. Just based on the bit of information you posted I would guess you do not, but it's definitely worth researching and asking questions!
Second, OPK's cannot confirm ovulation, they simply tell you when your body is gearing up to O. Only temping will confirm ovulation for you. So I highly, highly recommend you start charting your basal body temperature and cervical fluid to see what is actually happening with your cycles. To get started, pick up a copy of Taking Charge of Your Fertility and a basal body thermometer from your local drug store. The book is amazing and full of information I never knew about my body. Charting is such a powerful tool that will tell you when you're fertile, when you ovulated, how long your luteal phase is, when to expect AF, if you're pregnant, and if there is anything of concern happening with your cycle. You might be able to tweak your diet or exercise routine to help with issues you're having. You can log your data on a free site like www.fertilityfriend.com so that you can share your charts on this forum and we can give you tips, advice, and help deciphering anything that is confusing. It takes several months of charting to get a good feel for it and for what your typical cycle looks like. Charting will also arm you with information to give to your doctor if you decide to pursue any reproductive technology/medications, etc.
Personally, I would hold off on taking any medications before I knew what was happening with my cycle. But of course that is a very personal choice. TTC for 4-5 is really not that long when you take into consideration all the statistics and the fact that you're dealing with irregular cycles. Many women without any fertility issues take months to conceive as well. Usually crossing the one year mark is when you might consider yourself dealing with infertility issues. That being said I know how frustrating it can be waiting each month and hoping for that BFP. There are many women on this forum who can commiserate with you for sure! There are several different threads you can feel free to join based on where you think you fit in. Some are age based, some are for infertility issues, and some are based on where you are in your cycle (waiting to O, in the 2ww, etc.). Look around and jump in! Keep posting your questions and good luck!