I am not a good cook, so you're not alone. I often say the only reason I have a kitchen is because it came with the house.
Two suggestions. One is to try out some of the "diet meals", such as Smart Ones, Lean Cuisine, etc. Some of these are good, some not so. I don't eat them all the time, but I do have one now and again, especially when I'm really busy, because they're quick and easy...just pop them in the oven or microwave and that's that.
The second is to experiment with salads, and try to ensure you include a protein source along with the salad. I favor tuna, chicken or baby shrimp, but there are other choices since you say you're not fond of seafood. Salads don't have to be boring. Indeed, they're often my go-to meal. Below are some of my favorites. Most of these are between 400-500 calories and could serve as a main meal for supper (or whenever you eat your main meal).
Chicken Ceasar: Made with the usual romaine lettuce. I use a no-fat/low-fat Ceasar dressing (Renee's) and I skip the bacon bits. I include diced chicken and I often include some salad shrimp (not sure if you like shrimp). I usually also chop up a hard-boiled egg and mix it in with the salad. Yummy!
Spinach Salad with Chicken: Baby spinach, sliced strawberries, blueberries, diced chicken, sliced apples and a sprinkling of blue cheese, all tossed with Renee's Pear and Blue Cheese dressing (you don't need much dressing since baby spinach coats well with just a bit).
Spring Mix Salad with Tuna: I use light tuna mixed with no-calorie (Walden Farms) mayo, but you could substitute chicken if you don't like tuna. I add the tuna mix to the spring mix, along with avocado, tomato (you could substitute cucumber), mandarin orange slices and a few dried cranberries. I then toss with a low calorie Italian dressing. I note that the tuna/avocado and mandarins add a fair bit of moisture to the spring mix, so this salad needs very little dressing.
Waldorf Salad with Chicken: Any type of lettuce, mixed with celery, apples, cranberries, walnuts (you could substitute something else given your nut allergy), a sprinkling of blue cheese, diced chicken, and tomatoes (again you could substitute), all tossed with a low calorie balsamic dressing.
The one thing about most of these salads is that they include a bit of fruit, which adds to the flavor and satisfies my sweet tooth! None of them takes more than 5 or 10 minutes to put together, so they're quick and easy.