Talking to parents about babysitting, does this sound alright?

Wow, I want to meet you. I'M 17 AND ALSO 4'9"!!!!!!!!!!!!!!! Literally have never met someone my age my height or shorter. Wow!

But I wouldn't mention it. Does she know your age? If she hasn't asked yet, then don't even bother. I understand because everyone thinks I'm like 11, but when you talk they realize you're a lot older.

There is no need to warn them in advance. I assume this is just a meeting with the parents, right? They have not officially hired you yet, have they? ... They can decide when they meet you if your height or anything else would be a problem.

If the kids are young, they may even see your size as a benefit. Less intimidating. If the kids are older and not always well behaved, they may be concerned about how well the kids will respond to you. Otherwise - it should not be a problem.

Just make sure you dress nice (clean clothes, hair brushed) and bring your ID and any references that they may want to see.

There is no need to "warn" anybody about your height. You might come across as insecure. You are the size you are and your height has nothing to do with your qualifications.

I wouldn't say anything about your height, as doing so sounds insecure/lacking in confidence.

Besides height or lack of, doesn't have anything to do with maturity, or responsibility.