Problems eating enough

Hi :h1)
I've been noticing lately how hard it is to eat enough for breakfast so that my protein and carbs are at the right amounts. I get full after eating two thirds and when I try really hard to eat it all up, I gag and feel all nauseous. Am I doing anything wrong? Anyone else having the same problem?
I calculated that I need about 20grams of protein for breakfast. It's really.. I mean REALLY hard to get it all down! :s10(
I've been on step one for about 13 days now btw.
Is this a huge issue or should I just eat as much as I possibly can?
I'm on a very tight budget too and that doesn't make matters easier...
My mood feels stable and energy levels are ok (but could be better).