I don't think they are stretching and if so, not extremely much. They look different from each other: the tall ones are indeterminate varieties Start and Nelinka. There are two dwarfs: Arctic Rose and Sophie's Choice, naturally they aren't as tall as the former. And I also have a determinate plant of Mongolian Karlik. That plant isn't in the pictures as it is on another window sill. MK is just 15 cm tall, but very broad. Yes, more light would definitely help, but the pictures are much darker than reality. In fact it's 3 - 4,000 lux.
As to smaller fruits, you are absolutely right. They have always had smaller fruits than the ones in the garden. I take it for granted. But size is not important to me. I grow them for a very early harvest and for keeping myself a bit busy in winter months. Actually, they are quite expensive to grow as it is.
Milan HP
P.S. I am sending pictures of them before they were transplanted taken on Dec 28. They don't look leggy to me.