Even if you're irregular, you can still determine when you're ovulating. Buy a good book on natural family planning and figure it out. Clean out your system of any toxins that may be hindering implantation. Check out my 'No Morning Sickness Cleanse' article in order to achieve that. Additionally reducing stress and workload will move things along.
Optimal nutrition is Key.
One that is low or absent of refined foods is best. Cut out all fast food and packaged snack foods. Check out my article 'Eating in Harmony'. If you suspect that something physical might be in the way, such as low sperm count, blocked fallopian tubes, scar tissue, etc., see a practitioner to rule out those possibilities. Start with the most natural, non-invasive therapies first and make medical intervention and pharmacueticals your last result.