Every year I grow many tomato plants. I never have trouble getting the plants to grow, they get quite large.
I noticed with some varieties, like big zac or reistomate, I get huge plants but small fruit. I would like to get the fruit much larger for the tomato contest coming up.
I don't cut off suckers, I tried that once and seemed to get almost no fruit and thin stem growth that flops over. I read determinate tomatoes you shouldn't do that, but indeterminate you can, not sure what kind mine are.
There is also a way to prune seedlings but I never learnt how to do this so my plants are tall and thin shape.
Not sure how often to fertilize, I use Jobes tomato and vegetable granular fertilizer.