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How can I show that this language is not regular?

$$ L = \{a^n (ca)^m b^{n+1} \mid m \ge 0 , n \ge 0 \} $$

This is my attempted solution:

Assuming the pumping number to be $p$ and making $m=0$

the language reduces to $a^p b^{p+1}$ so $s=a^p b^{p+1}$

let $s=xyz$ where $y$ is not $\epsilon \\$

$y=a^k$; $0 \lt k<=p$

$x=a^q$; $0 \lt= q \lt p$

$z=a^{p-k-q}b^{n+1}$

so with this definitions, $xyyz$ cannot be part of the language since this would be written as

$xyyz$=$a^qa^ka^ka^{p-k-q}b^{p+1}$ = $a^{k+p}b^{p+1}$ which means there is always an extra $a$ which is not in the original language.

Is this approach correct ?

qboomerang
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