Is 21 too young to marry

Getting married at 21 ?!

Why not?!
I just signed up after reading your post.
So I think everyone has to know for themselves when to get married. Some do it early, others later or not at all. That is never a guarantee.
You can still be surprised negatively by your partner even after years of marriage.
So we got married in August (I 21, he 26).
I don't see the problem, we love each other. I am not naive and I know we will try everything to keep the fire from going out - of course it can go wrong. But I would regret it even more if I had to be with him for another 10 years and always had to think about whether to marry or not.

Because of the celebration: you have to know for yourself how important a big celebration is to you. If it's not that important, just celebrate on a small scale, then it doesn't get too expensive either.
I also know a couple who partied very small (only with parents and siblings) and don't regret it.
Maybe you want to get married in church later, it will usually be bigger anyway.
We only wanted to go to the registry office, so we organized a nice celebration right away. It wasn't cheap, though, because it was in a castle and with a wedding dress, etc. All in all, about 10,000 euros - so I think you can do without it if the money is not so liquid .

But let me know how it looks now!

I like it