Flying question if you have a toddler

meangene

Would you be comfortable carrying a 20 month old as a lap child at this point? Only a 1 hr flight.

I have a wedding I'd like to go to at 23wks, but DH can't come. I can't manage the 8hr drive by myself.

I don't mind buying an additional seat for DD, but Southwest seats are only 16in wide and my car seat is 20+ in wide. 

So, maybe my question is - Do you have a car seat that you can use on a plane? Mine is approved for flying, but just too big.