I don't have an ED but how do I stop feeling guilty about food?

I can undertsand Norwegian but its easily to write this in English so I hope you don’t mind. It all started one year ago when I got my surgery, that week I went from weighting 50 kg to weighting 45kg and everybody told me that I became very skinny. I was happy to hear that and I stopped eating a lot as I used to, I started couting the hours between my meals and often forgot to eat. But, there was a change in summer. I started being more positive and I forgot about the whole food thing. Now again I’m starting to feel guilty, its not every day thought. One day I can eat just fine but others make me nauseous when I look at food. I know this is weird to say but I used to love when people would tell me that Im underweight and I have always dreamt of becoming skinny. How do I stop this thinking? Even if it goes away it comes back again and I don’t want to get an eating disorder.