Only 20 lbs?!?!

Rebecca • Mom of 5, 3 girls and 2 boys. This is my 5th pregnancy after we lost our angel of February.
I had my confirmation of pregnancy appointment Thursday. She told me the goal is to gain 20 lbs through the whole pregnancy. She says this following, "Eat every 2 hours". Now how is that possible?!?! I have already gained 2.4 lbs in the past week and I'm only 4w4d!! 
I'm so stressed out and having anxiety over this! I gained 30 with my first, 35 with my 2nd and 85 with my 3rd!!