I'm going to be a little harsh here. Apologies in advance if I upset anyone.
There is no way you're going to lose on the SW plan if you have one meal a day. You're not having any Healthy Extras, no Syns, not very much free food. Your diet is not healthy. It's not balanced.
/telling off over
That's the reason you're not losing hon. If you can't eat much without feeling sick, PLEASE go to the doctor. You shouldn't be feeling like this - food is a massive part of life and you should be able to enjoy the healthy food that you should be eating!