Hello we have been ttc for a few months now. I have been using the sainsburys ovulation kits for two months testing daily. However, the kits are not picking up when my egg is due to be released and I get negative results every time. Im still getting periods so I know that an egg is being released. I am testing at the same time - 530-6pm and do not drink too much before hand. Do these kits work? Are some better than others?