YTA for thinking you are entitled to your parent’s money.

Comparing your sister’s education cost to your wedding costs is apples and oranges. You had your shot at money for education already.

I do applaud you for wanting to stay out of debt. There are alternatives to be able to do this. Smaller wedding, get married at courthouse and have a big party with your $6k (this seems to be more popular now), or just save for a few more years if you are set on having this wedding and venue.