Healthy weight loss for pregnancy

Hello I've been trying to loose weight whilst ttc as I feel like my bmi is a little high and bringing it down will also help me to concive, any suggestions as I've tryed slim fast and tablets the doc gave but there not safe to take anymore, also I gained weight in pregnancy with my first and this is the heaviest I've ever been but no amount of ex resize and eating right is helping me loose weight so trying to think outside the box lol .. Any suggestions would be greatly appreciated x