What are my options for transitioning from an Education Visa to a Non-O Marriage Visa while pregnant in Thailand?

Okay, I don't think you're gonna be able to go from an extension of stay based on education to one based on marriage to a thai inside the country. I say that because I've never seen them change a reason for an extension from education to something else. :/ Every person I know (a LOT) who was on an ED visa extension and went to change the reason, had to leave the country and either get a 30 day visa exempt stamp so they could apply for a Non-O inside the country OR get a Non-O outside the country from a thai consulate

I think you're gonna hafta cancel your extension, and then go to the border to get a 30 day visa exempt stamp THEN you can apply at the immigration office for first a 90 day Non-0 visa based on marriage and after you get that you can apply for a yearly extension of stay.

I hear it is much easier for farang ladies marrying Thai males than farang males to Thai ladies. Not sure of the truth of this.

Two options: Ask Immigration to convert your reason of stay into a Non Immigrant O visa based on marriage with Thai National or if you can not travel get a letter from the doctor and apply for Extension Of Stay based on medical reasons.