What did you wear under maternity gown?

Marli • Lottie Mae norm 3-23-20. Liam Thomas🌈 born 4-7-17. Angel baby 5-4-16. Hubby & I married 11-1-14. Have two Pomeranian `babies`.
For those with the sheer skirt or split maternity gown...what did you wear underneath?
Where did you get it?
What size are you?
Did you have a hard time finding something?
I tried these shorts today. They're from pre pregnancy. They're uncomfortable and don't fit. But it's VERY SHEER. 
I have on nothing there. But I can't do that for the shoot. And if I want to wear it to my shower, I can't do that either. Being plus sized makes it twice as hard. 
Suggestions?