I don't recall when I wasn't broody!
I'm the eldest of 3 and of many cousins and have been caring for others babies and children since I was quite young, and willingly so.
Then from the very start my periods were bad. I had a "gut feeling" something was wrong and I was correct. I had endo which went undx for 14 years.
I had my first mc at 18 but that pregnancy was most definitely unplanned as broody though I was I'm not an idiot! I was on the pill taking it fully correctly.
After that unless actively ttc I used 2 forms of contraception.
My friends as a teen all knew and felt sure I'd be the first to be a mum, they even thought I'd likely be a teen mum
which they almost got right.
When I met ex I was clear with him I wanted children and that I didn't want to be an older mum (and I meant over 30) He's one of a big family too and that didn't phase him.
But I also was clear I wanted to be married first and he was less sure on that, but we were quite young when we met only 19/almost 20.
Once we were married I was keen to get cracking but several factors got in the way including his deployments (he was army). Eventually "calendars cleared" and we ttc and that pregnancy too ended in mc.
That was also when the endo was dx and I had to have several surgeries and medical treatment and had to wait until we were given go ahead to ttc again.
Fell pregnant with dd, but it wasn't plain sailing. I loved being pregnant but medically it was very touch and go.
Ending in emcs and both of us almost dying and my losing a lot of blood.
Dd was in scbu and I was very poorly.
Then I was told the issue that had occurred with me was a rare condition that recurred with subsequent pregnancies and could be fatal so I was "advised" not to get pregnant again. 
So...I'm 47, peri and I'm still broody.
I'm looking forward to becoming a gran hopefully at some point but it is a source of great sadness to me that I couldn't have the big family I wanted.
And I was in my 20's.
I have to say whenever I hear of couples in a committed relationship, both got good jobs, finances ok and they're delaying ttc for other reasons I just hope they don't leave it too late.
Because while there were reasons I had the problems I did which weren't related to age, age does increase the risks of:
Difficulty conceiving
Mc
Premature birth
Stillbirth
The child having health issues
There's a reason mid-late 20's is considered the medically optimal time.