Learn English – “Could you tell me what wrong is with” or “could you tell me what is wrong with”

"I don't have it on me" is a common thing to say in British English.

• Do you have it with you?

If the person has travelled somewhere, and they brought it with them - they might be holding it, but it could instead be outside in their car, or someone else might be carrying it. It is still "with them" because they can get it quickly and easily. It's not at home, or far away.

You might ask this for an official thing, like a reference number.

"Do you have the reference number with you?"

"Yes here it is" or "Yes, it's outside in my car, I'll go and get it"

"Thank you"

• Do you have it on you?

Are you carrying it yourself, in your pocket or bag? If it is outside in your car, then it is not "on you". If someone else has it, it is not "on you".

You would ask this for a quick request, one that you don't want them to have to go and get something.

"You have a pocket knife - do you have it on you?"

"No, it's at my desk"

"Nevermind, don't go and get it. I'll just tear this box open".

"could" is a modal verb, and it requires a short infinitive after it.

So it is correct to say:

You are the best mom anyone could ever have.

I think it is more usual to say:

You are the best ... anyone could wish for.

or

You are the best ... anyone could ask for.