It looks like you're on the right path, and your s are not that bad!! There are a lot of different versions possible, some narrower and some wider, some have the dot below the entry stroke, some have it crossing the entry stroke...
He is what I'd recommend, but remember it's just the way I like my s :
The entry stroke looks a bit stiff, try curving it slightly to the right when you get to the waist line. Then retrace a little to get back to the waist line before doing the downstroke. I think the lower curve should match the curve of your other letters (o, c...), I'd say I like it a little wider than on your pics. Then finish wherever you like with a dot.
I can't attach a picture, but I hope you can understand my explanations...
Anyway, don't worry and keep on practicing, it'll come !