Obviously it depends what you put in your soup, but an average bowl of soup that’s just vegetables, no meats or fats or grains, typically has 100 calories or so. Maybe a bit less, maybe a bit more. You could double that by adding a grain - rice or barley, perhaps - and some kind of thickener (flour?) and maybe some cream, but it’s still not a high-calorie meal, and has very little protein.

A slice of seeded bread might be anywhere from 120-ish calories to 250 calories, depending on the kind of bread, and what size your slice is. If you’re asking about pre-sliced bread, something like Hovis Seed Sensations, that’s about 130 calories. Plus another 30 or so for a teaspoon of butter, if you’re planning on buttering your bread.

You said a slice of bread per day. (You might have meant per meal.) One slice of bread per day, plus butter, plus three average-sized bowls of an average vegetable soup come to 460 calories. Maybe as many as 760 if you add a grain and some cream to your soups. Hell, maybe even 1000 if you add a lot of grains and cream. But probably not more than that. It’s really hard to get enough calories just eating vegetables. (I have cancer and a very small stomach capacity, but still have to eat vegetables to get vitamins and keep everything moving, so I know this first-hand.)

I’m not willing to give advice about caloric needs without knowing you. Standard, one-size-fits-all advice says 2000 a day for women and 2500 for men, but that doesn’t take into account whether you’re 5’1 or 6’3, or whether you’re sedentary or walk 10 miles a day, or any other activities, not to mention age and other things that may affect metabolic rate. But you would be an extreme outlier if 1000 calories were enough to keep you in good health.

You also need more protein than you get from vegetable soup and bread. You could add some meat or tofu to your soup, which would help. Protein needs vary a lot from person to person, and are affected by a lot of things, both things we expect (age, sex, activity level) and things that we don’t (I found out that my expected protein needs are currently about 50% higher than normal because of radiation therapy, for example).

Unsolicited advice ahead, skip if you like: It sounds like you might be either experiencing financial difficulties, disordered eating, or that you’re new to meal-planning and not sure what your dietary needs are. If it’s the first, I suggest checking out food banks in your area, or apps like Too Good to Go or Olio, where you can get food cheaply at the end of the day. If it’s the third, you can try using an app like My Fitness Pal (or similar) to find out your rough nutritional needs (based on age, sex, body size and activity level) and to log your food and see what you’re getting vs what you need, and if that doesn’t help, you might see a dietician. If it’s the second…therapy is all I can suggest.