my husband chose the wrong health insurance plan…all hope lost?

I’m going to do my best to keep this from being a rant about this issue because I’ve already had a panic attack. I opened a billing statement for some labs and appointments for my pregnancy and neurologist and found myself horrified; my husband chose a high deductible plan with his company in November. Every year we get a low deductible plan ($3,000) because i see multiple specialists (two neurology depts, allergy and GI) and hit the deductible with medication alone by March. For some reason, he accidentally selected a $15,000 HDHP. This is a high risk pregnancy with labs and ultrasounds once per month and I’ve just found out that the majority will be out of pocket until we hit $15,000. I didn’t enroll in my company’s in December because he assured me I was on his. We just had home damage where we had to take out a loan, and need to get a car that’s going to work for the baby, so I am in a panic with where this money is going to come from.

Is there anything I can do? It almost seems like a stupid question. I doubt HR will let me get on ours now -I’m a teacher, as open enrollment ended in December. My mind is blown that he could do this and I’m totally lost.

Thank you