You can let baby sit in car seat for a while after it eats...
Typically if this is happening it could be a case of acid reflux. Very common amongst little ones. Try elevating her mattress about an inch or two and see if it makes a difference, and wait about 20-30 minutes after eating before laying her in her back. Most babies grow out of acid reflux. If it gets worse or these things don't help, I'd bring her to her pediatrician. Best of luck girlie! And congratulations!!!!!!!!!!