As a coeliac, you actually already cut out a lot of the stuff that you should drop.
Do you eat the gluten free bread and substitutes? These can actually be high in calories I noticed after spending a month going gluten free to test for intolerance's.
What you should really be doing is trying to turn most of your food fresh, meaning minimal packaged foods, processed foods. So I wake up and have 3 boiled eggs/scrambled on a wholemeal thin, which I did at one point use the genius or triple seeded bread. I will then have a banana as a snack mid morning. Lunch will be a chicken breast with half a pack of tilda rice and either beetroot or asda mixed bean salad. At 3pm I will have FAGE 0% yogurt 100g with 10g of Rowse Honey and some cinnamon. Then dinner will be Salmon/ Herby Baby Potaoes/ Veggie Steam Bag, or Turkey breast/ half pack tilda rice/ green beans/ cottage cheese, or Lean Mince, gluten free gravy, veggie steam bag topped with aunt bessies carrot and swede mash. If I went to the gym after dinner I will have an Asda chocolate covered rice cake, and a 40 cal options hot choc.
All of that is around 1500 calories depending on the combination.
The only thing you would need to change is the bread at breakfast, and the gravy, which btw the old bisto version (not the granules) is gluten free.
I know I say try and go fresh
then talk about my steam bags
But I just can't get veggies to live longer than 2 days anymore, so the frozen steam bags work for me. I like the Birdeye family favourites one. The Tilda Rice is also a god sent for me because of all the different flavours, plus my rice making skills are crap.