Welcome to minimins!
SW is fine for anyone wanting to lose weight, no matter how much, or how little.
If you were to join a SW class, you would have to have at least 7 pounds to lose or they won't accept you. Obviously, that has to be within the healthy weight range, and they will not allow anyone to join if the weight loss will bring them below that weight.
We had one lady join our class wanting to only lose 10 pounds and she lost 4.5 in the first week.
So, go for it, and good luck!