As you are a vegan/vegetarian you need to learn about the carbohydrate content of various foods and about the different types of carbohydrates. There are many and they all affect you differently. The only real way to learn how, is to test. Most of us get our own meters at some point.
Pineapples are a big no no I'm afraid. I stick to northern fruits, nothing tropical and I even avoid watermelons and grapes. So, berries, plums, apples, pears and so on. Avoid all highly refined grains and stick to the more complex wholegrains; brown rice, pearl barley, pinhead oats, wholegrain rye and so on. If you can go back to vegetarian and have some cheese, do so. I personally can't live without fish. I always get my lowest readings after those meals.
Beans and pulses generally are great for diabetics. Lentil curries, chick pea curries, fantastic. Plus, you can make lots at one go, separate into portions and freeze them. Salads with feta cheese, olives, loads of fresh tomatoes, rocket, red peppers and some beans, great.
Potatoes are very starchy and if you mash them or use softer flourery potatoes, they go straight into the bloodstream. In fact, the digestive enzyme ptyalin or mouth amylase starts to break it down and turn it into glucose as it is sliding down into your stomache. The enzyme is in your saliva. If you must eat spuds, boiled new potatoes and not too many is the way to go.
You have to test and learn. It takes a bit of time and effort and costs a bit of money, but it is defintitely worth it.