Some friends of mine tried for 7 years - nothing.
They thought enough was enough and went to get specialist help in the form of IVF. They had the consultation, got the treatment planned.. etc etc. 2 weeks later she was pregnant naturally. A couple of years later they decided they wanted another, but this time they didn't 'try' they just took away the barriers and let nature do it's thing. She was pregnant within 4 months.
When we decided to have children, I was very keen to avoid the stress of trying, and just let things happen naturally. Within 5 weeks we were expecting our son - the same thing happened 3 years later, and we got a daughter.
My advice is to relax, stop thinking about the right time of month, temperature, wind direction and just enjoy the bumpy bumpy without the hassle of contraception. Just don't do it every night, as this can have a negative effect on the quality of your swimmers.
I assume that you've cut back on alcohol and cut out smoking (if you do) and looked at your diet - these can have a big impact.
Good luck and enjoy your freedom while you still have it.