Definitely. I felt that my baby was squashing my stomach too much for me to take much food or drinks. What I did was to take smaller meals and more snacks in between meals to make up for the calories. But if you still can't take much don't stress over it too!
Yup! My appetite decreased during third trimester too (towards the end) till I go into labour. But had bad cravings for sweet stuff.
Your baby taking most of the space in your stomach. there for your appetite can be reduced. Take small portions more often.