'But, no matter' Versus 'But, doesn't matter'

[Tom]

Hi

Are the given expressions correct and interchangeable?

1- I have nothing to eat...but, doesn't matter!
2- I have nothing to eat...but, no matter!

Tom

[Mister Micawber]

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I have repaired your punctuation and supplied a necessary pronoun. They are now essentially synonymous:

1- I have nothing to eat, but it/that doesn't matter!
2- I have nothing to eat, but no matter!
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Native English teacher at Mister Micawber's

[Pamela]

Why did you place commas after but, Tom? I wonder.

[Tom]

Mister Micawber wrote:

I have repaired your punctuation and supplied a necessary pronoun. They are now essentially synonymous: 1- I have nothing to eat, but it/that doesn't matter! 2- I have nothing to eat, but no matter! .

I liked the collocation essentially synonymous!

I would like to ask another question:

When in ( it is) no matter, the it part can be optional, why not in (it) doesn't matter?

Tom

[Mister Micawber]

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