Don't take up knitting .. I thought we had solved your tomatoe woes .. it sounds as though you have done everything right apart from one thing.
Emeritus has already mentioned it ... feeding before the flowers have appeared. If the tomatoes are fed too soon they may well sit there happily without developing further. It may sound daft but a little bit of stress may get them going ... as in, don't feed them anymore and only water them when the leaves droop through heat exhaustion.
Last year I grew a sqaush plant, it was placed in the centre of a pile of manure. Plenty greenery appeared but no fruit. When I asked a friend if I was going to get anything from it. He told me to stop watering it every day (bearing in mind this was late july and sweltering) and give it some stress which will force it to flower. It went on to give me about 10 large squashes.
I will attach some photos of my tomatoes soon and it will give you some encouragement. Tonight we will be eating the very first ones picked this year (dwarf maskotka's grown outside).