Hard time

I am having such a hard time with my 16 month old. He wants everything he can’t have and it makes him so mad. He screams when being put in the car seat and throws himself on the floor when he doesn’t get his way. Previously it was only every once and awhile and the past week it’s been almost every day multiple times a day!! He’s my first baby and I’m at a lost. Anyone have any ideas??? I’m almost 5 months pregnant and that does not help my patience level with him!