Im pregnant and hungry but my mom wont let me eat?

I was under weight when I became pregnant, I am 16 or 17 weeks. I habent eaten for 4 hours and I feel sooooo hungry but mt mom won't let me eat until dinner? Its ONLY an hour away but my stomach is empty and in an hour I will have waited so long to eat I might not be hungry and just feel bad instead. She said if I bought the food I could eat whenever... Which she's stupid because I do help buy food when I have money on my ebt card. All I wanted was a damn tomato... But no its for sandwiches. I'm sure tomatoes are so expensive I can't buy another 10 at the store tomorrow. I'm hungry and pregnant and I want to eat when I'm hungry. Not when she says I can like I'm 10. Its bad enough I had to move back in due to spliting with my cheating fiance. she physically is standing infront of the fridge not letting me eat one slice of a ridiculous tomato to curb my hungry until dinner. I'm frustrated.