just my non medical personal opinion but u should be ok, if u do feel abit giddy have some fruit like a banana or just a cup of tea.

Stop thinking and worrying about it (i know it's almost impossible) you'll b ok, instead of looking at your food as set meals at certain times of the day, just eat little and often, even if a sandwich takes u 2 hours to eat just take your time.

Have you talked to your doctor about your lack of appetite?