I raised my tomatoes from seed (around March I think). Planted in the ground May 6. The tomatoes have grown to a handful size but have sorta stopped growing bigger. I’ve been using light fertilizer every two weeks. I’d hate to kill them now but may go to a higher dose in a few days. I expect to pick by July 15. I’d like them sooner but . .
What are you fertilizing with? At this point in their growth, make sure your fertilizer has a higher ‘middle number’ in the NPK of whatever you’re using.
They want Phosphorus right now for blooming and fruiting.
Any ‘tomato’ fertilizer should give you what they need.
Also - if the plants themselves are looking puny - are they getting enough sunlight? 8-10 hours a day is what they need.