I would say the odds of you getting pregnant from this act alone are very low.
If he hadn't ejaculated yet, then he only could have had precum on his fingers, which is thought to contain zero to no sperm.
http://en.wikipedia.org/wiki/Pre-ejaculate
Probably less amount of semen has entered you via fingering that usually happens during coitus interruptus (pulling out), which has been used as a form a birth control with good success for ever (well, its as successful as pulling out in time). The cases of women getting pregnant from precum alone are very rare.
Whats more, is that even if there was small amounts of sperm, your vagina is a very hostile place to these little swimmers, and without the support of a good dose of semen, they are likely to have perished in the acidic environment as the fingers moved its way upwards. Delivery by penis has the benefit of surviving from the tip of the penis. When fingered, the sperm has an extra 5-6 inches of hostility to overcome.
I can't say anything to the irregularity, but if I was in your position, I would be taking deep breaths and repeating the rational above in my head to keep me sane until my period came.