So your Dad is not a permanent resident? You can't get over based on the work visa (unless it allows for dependents), but if he ever does become a permanent resident, he can petition you.
If you are under 21 (F2A), the wait time is about 2.5 years (they are allowing folks from Feb 15, 2010 applications), and if you're over 21 (F2B), it's about 8 years.
There are intricate rules about when you apply vs when you're approved for the cut-off age (something like your age can be frozen in time as long as you apply before you're 21, but they might have changed the rules), and I would highly recommend visajourney.com and look under the forum, "family members of permanent residents" which can help answer all those questions.
Of course, if the economy picks up, the visa retrogression for nurses may pick up as well. Or, if you marry a US citizen or a US permanent resident, you could get permission to live/work that way.
Good luck! I am an American nurse and married a born/raised Brit. I recently got my nursing registration with the NMC and while it was a lot of headaches, I didn't need to go through nearly as much as you guys, let alone take a test! Keep us posted on how things go.