Healthy low calories breakfast, lunch , dinner option for vegetarian?

Wow, that's a big question!

You might consider joining this group here for vegans, vegetarians, and plant-centric omnivores:

https://community.myfitnesspal.com/en/group/145477-herbivores-of-mfp

The group itself isn't very active anymore, but there's are threads there that may give you some ideas, such as:

https://community.myfitnesspal.com/en/discussion/10900163/what-did-you-eat-today-pictures-welcome#latest
https://community.myfitnesspal.com/en/discussion/10917349/whats-your-favorite-vegan-recipe-right-now-please-share#latest

I've been vegetarian (ovo-lacto) for over 50 years, thin to fat to obese and back to thin again (where I am now, in year 8 of maintaining a healthy weight at age 68).

There are a few special nutritional challenges for us as vegetarians, but fundamentally for us the process is like it is for everyone: Start logging your food as you eat it now, notice things that "cost" too many calories for the nutrition, satiety or general happiness they bring you. Reduce portions or frequency of those, and bring in other foods you enjoy that are more calorie efficient and that help you reach your goals.

Really, no one else can give you the solution. You and I are both vegetarians, but I'm betting we don't have the same food preferences or lifestyle, so what I do might not suit you in the slightest . . . but I do have confidence that you can figure it out, if you commit to it, and keep working at it patiently and persistently.

If you have any more specific questions, I'd be happy to try to answer.

I'm cheering for you to succeed: In my experience, the results are worth the effort!