miserable strawberries

[Salina]

The strawberries I've grown this year are all really small, some of them only about the size of cherries. the ones I've seen in the shops are huge ones about the size of small plums. Are they a different variety or do I need to give mine some plant food or something? They are also quite bitter but I suspect that's down to lack of sunshine.
Thanks in advance for any advice!

[veg4681]

I only had one cherry sized strawberry as this is my first trial in first year. I would think that if they've gone red already then they're ready for eating and not likey to grow any bigger. Mine didn't grow any bigger so I ate it.

[Flummery]

It can be variety but you also need a fair bit of water - not a problem this year. Maybe it's becauee they are young plants? They reckon they yield best in their 3rd year.