Daisy, I am a small lady who used to be a very keen, quite serious, cyclist until age and other issues overtook me.Hi. I'm looking for a step through as a small lady. Ideally a 17inch frame. I don't know how frame size
equates with wheel size. Do you?
There is a far more limited range of sizes available in e-bikes than in 'proper' bikes and you might want to be looking at a step through with 24"wheels, which is certainly what I'd be doing if I didn't need a folder. As a shorty, you'll definitely want to be considering both your inside leg length (saddle to pedal) AND your reach - to the handlebars. A bike's no use if you can't both pedal and steer in comfort and simultaneously!
If you can try several bikes - and note accurate measurements - you will get a good idea of the sort of measurements you are looking for. The larger budget you have, the more likely you are to find something to suit. Alternatively, if I still had my old Isla bike (13" frame) I'd probably be buying a conversion kit, so if you already have a bike that fits you, you might want to look into that.
Hope that helps!