No, the expected answer is 1000, not a kata issue.

No, you're not, the first one is your wrong answer, read the description again. Not a kata suggestion btw.

If the string already ends with a number, the number should be incremented by 1.

Your solution is incorrect - debug it.

Not a kata issue. See https://docs.codewars.com/training/troubleshooting#post-discourse.

Not a kata issue, please check again the requirements for the kata, especially:

If the final result is longer than 140 chars it must return false.