Extension of B2 visa and future entery

[bellagabi]

Hi, I have a 10 year multi-entry visa to the US. I have been in the US 5 1/2 months now. My I-94 form will expire in two weeks. Two weeks ago I applied for an extension of stay till May 2011. My son (20 months old) and his dad are US citizens and his dad works in Law Enforcement. We wish to get married after I return to my home country in Scandinavia (need to finish my exams). I thought my exams would start mid May next year, but now it seems like one is as early as February 2011. I see the Vermont Service Center has a 3,5 months expected processing time. I might not get an answer before I have to leave in February. Should I write a letter to the USCIS explaining I need to travel earlier then expected?
If i leave in February without receiving an answer, will I get problems with getting a K1 visa and reenter the country?

Thank you for your time!