Each to their own.
I was married at 22 (only just 22 too) and had dd at 28 but would have been a mother sooner but I have Gynae issues.
We're divorced now yes but I don't think it's because we married young, plenty of others married older and split for the same reason (his infidelity).
Hadn't intended to marry young and certainly when we met neither of us were even looking for anything serious we were just on a night out and introduced by mutual friends, as many people meet I suspect.
Dated casually at first, then circumstances changed and we discussed if it was going to be a serious relationship or not and we decided together it would be and things developed as they tend to from there.
Among my friends and family there are maybe half a dozen who are or were with their 1st serious partner/spouse a long time.
The ones where it's "were" sadly were bereaved rather than the relationships breaking down, indeed in one case that was part of the motive for them marrying as quickly as they did. He had a life limiting illness and they didn't want to hang about. They had 15 years together before he sadly passed due to complications.
The ones that are still alive are still together and very happy.
But yes I also of course have some who've not met their "forever person" until they were much older for various reasons and are now settled and happy in their 40's and 50's.
There's extremes both ends and unfortunately they both had people make snarky comments and judged without knowing the people well or the full facts of the situation.
Eg the couple with the sick guy who died married at 17 with the full blessings of both families as they knew the situation, people who didn't even know he was sick (you wouldn't have known from looking at him or even interacting with him if he was having a good spell) passed comment when they should've kept their traps shut. As it was they were "lucky" to get the 15 years they did as that wasn't what was expected. She has remained single since, and they had no dc as it's a genetic condition and they felt that it wasn't worth the risk. They were judged for that by those who didn't know the full story too, at least until he passed .
You don't know what's going on in people's lives, if they're actually making comments then absolutely set them straight (politely - if only to give em enough rope!) but also acknowledge they maybe envy you, or are even concerned for you.
Statistically younger marriages are less likely to last but it's not true for everyone and only you and he know for sure.
As long as you are both happy and treat each other well that's all that really matters.