18 weeks and need to eat more

I had my second prenatal appt yesterday and everything I great with baby, but the doctor was concerned with my weight. I have lost 16lbs since becoming pregnant and I’m currently 189lbs. They are worried I am not getting enough calories for the both of us since I should still gain a little bit of weight. I find I get full after a meal and I’ve never been much of a snacker but I think I need to start snacking ! So with that being said- what are your go to snack ideas ? I work in childcare so has to be something I can consume quickly !