Will using the withdrawal method while im on the pill make my chances of pregnancy even less?

No. While there are proponents of non-hormonal natural birth planning, withdrawal method is not a reliable way to decrease your chances of getting pregnant. Many babies are conceived as a consequence of withdrawal method so stick to taking your pill regularly. If you really want to lower your chance of getting pregnant, make him wear a condom each & every time. Add'l benefit is lower risk of stds.
Yes, but use condoms. Yes, the withdrawal method in combination with birth control pills does decrease your chance of pregnancy but the failure rate of withdrawal is high. I strongly recommend using condoms as this is a much more effective form of birth control and is the only form of contraception to reduce the spread of sexually transmitted diseases.