EU-web vault: https://vault.bitwarden.eu/#/login
US-web vault: https://vault.bitwarden.com/#/login
Try both! (if not already done)
And are you sure, you’re using the right email address and the right master password (no typo etc.)?
If you have an “emergency sheet” with your master password on it - compare it with what you actually type in.
PS: Maybe slightly outdated, I would think, but I found some further things you could try in this post: How To: Master Password Problems and Best Practices
PPS: Maybe for better help: Are you self-hosting? - My guess would be, you are not… (?)
PPPS:
If I understand you correctly, you wanted to make your master password shorter so that you could type it in better on your tablet? Not your problem at the moment, but I would advise against making your master password less secure by shortening it (but it depends on how strong it already is).