How to stop DDog nipping me when she wants attention?

[DuvetDayEveryday]

She's a 17mo chihuahua x Jack Russell. Perfect in every way apart from this. Every so often (a few times a day) she'll come up to me or DH and nip at our hands or legs. Usually it's because she wants us to throw a ball or play with her rope, or sometimes to let us know her bowl's empty (we feed her dry food throughout the day as after much trial and error it's the only way to get her to eat).

We've tried a sharp 'no', turning no our backs and ignoring, putting her in her crate for a 'time out', yelping, all the things the books advise. I thought she'd grow out of it but so far she hasn't.

She's otherwise beautifully behaved, has good recall, sits and stays, gets down when told. It's just this one issue we can't seem to crack.

Any advice?