Many of my plants yielded very few tomatoes this year

[Elliot]

I spake with the nursery where I bought my plants and they felt I used miracle grow potting soil which is too rich in nitrogen. I spoke with a local farmer who had amazing beefsteaks. He felt that I did not fertilize enough. A third expert felt that it was our hot northeast summers which did not allow for adequate germination of the flowers. Any ideas for next year?