Your losses are bang on what you can expect on SW. There's a limit to how much you can lose on any diet and you're doing really well. Just remember the weight didn't go on overnight it's not going to come off overnight either.
Drink plenty of water (or other fluids such as NAS squash). I didn't really understand how this would help with weight loss but I found this online:
"Your liver is the organ that deals with metabolising fat, and your kidneys deal with straining the toxins out of the water you drink. However, if you do not have enough water in your system already, your kidneys will not be able to do their job. In this case, your body shifts some of the work over to your liver. Your liver was dealing with fat, but now it has to do that AND deal with the extra filtering that the kidneys would normally do. So the efficiency of the liver is compromised, and it ebds up leaving a lot of fat in your body that normally would have been burned away"
Other than that, maybe try varying your days/weeks. Do some Red, some Green and some EE. Or maybe try doing full weeks of each to see which gives the best weight loss. Sorry if you already do that!
I have to be honest, last week, I was poorly and did no exercise - I was expecting a STS or a pound off at most, as I exercise quite a lot. However, I lost 3lbs...maybe try toning down the exercise a little and see if that helps.
If you search for 'Success Express' as well, that might help. I don't know the ins and outs of it but there is a fairly recent post that goes through it.