I need help with portion control!?

First off, I am not overweight and this isn't an issue of losing weight. I have always been a big eater, I never gain any weight. I stay right around 175. I'm eating myself into poverty. I eat large portions and it is killing my funds. A family sized hamburger helper meal will last me 1 setting. I eat 3 packets of oatmeal at a time. A pizza lasts me 1.5-2 meals. I just don't feel full unless I eat a lot. People keep telling me that grocery shopping is the most cost effective way to eat but with how I am consuming food, it just plain isn't. I'm not big on left overs and that probably leads to my overeating. I am looking for tips to tricking myself into feeling satisfied after eating less, that way I can save myself some cash and try eating a bit healthier as well. Thank you in advance for any advice!