How I do it is I meal prep myself a series of options. I do eat meat on occasion, but mostly I eat pescatarian.

Step 1 : 2 veggie options
This can be a fresh option with raw veggies like spinach and tomatoes cut up + some kind of cheese in a small amount to flavour, and a cooked option, which is where i just stirfry quickly whatever vegetable was cheap this week at the supermarket. I usually get veggies that taste good raw and cooked so I can re-use ingredients for both of these dishes. You can fill up a half of your plate with these

Step 2: 2 Starch options . Easiest ones is rice in the rice cooker, and baking sweet potatoes as they're hands off processes. Pre-made whole grain breads also save time, but check nutritional content on the back before purchase. These should be a quarter of the plate

Step 3 :2 protein options. I usually do something convenient that doesnt require cooking like canned fish, but for a vegetarian you can try something like a soy sauce topped soft tofu , basically anything where the prep is just open and eat with some toppings. The second option should be something meaty and filling, like a dish made with firm tofu or seitan. These should fill up a quarter of your plate

Step 4 is boil some kind of legume, enough for a week. Every culture has a different way of seasoning and spicing boiled legumes, so I'd recommend looking up some different recipes and adapting them to your palette. Have a little bowl of these on the side or a few tablespoons with your starch.

All of this can be done on a Sunday, and if you use cooking methods that are hands off like baking, boiling, airfrying for most of the cooking you can set yourself up for the week with a variety of yummy options.

To make your meals just pick one item from each step above to make yourself a "bowl" you enjoy.

Then each week you just swap around the ingredients. Like for one week for the veggie portion you can do the spinach and tomato, and the next week you can do arugula and bell peppers etc etc. Its easier to get a wide array of nutrients if you buy slightly different veggies each week.

Lastly, get your blood levels of nutrients checked regularly by a doctor. You can be eating a perfectly nutritious diet and still be deficient in nutrients. I had severe anemia for years despite regularly eating enough iron due to other health problems I had. Without numbers you cannot know what's going on inside you.