I've never heard anyone advise topping tomato plants when they are young. I had deer top one of my brandywines when it was about two feet tall, and that plant never really recovered. Some people top indeterminate tomatoes late in the season to encourage late tomatoes to ripen before the first frost. You should never remove the top of a determinate tomato.

Agree with Ohiofem. Tomato plants aren't flowers. "Pinching" doesn't not apply to them. If you didn't get much fruit last year it had nothing to do with any pinching you did or didn't do.

Production is determined by the growing conditions you provide and the genetics of the specific variety grown.

Dave

sounds to me like original poster has been reading UK gardening message boards since topping plants and suckering plants does not help production. It hurts production if you don't do it correctly you will get no harvest at all.