I can understand your point OP.
Me and my sister are only a year apart yet her children are 17 and 15, whereas mine are 9 and 6.
I went to college and Uni and entered a profession so that was my focus and priority, whereas she didn’t choose that path in life.
She had her children quite quickly with her boyfriend when they were aged 23 and 25, whereas I had mine at 31 and 34.
I look at my sister now who is 40 and practically has her life to herself as her children are pretty much self sufficient, whereas I’m 39 and still feeling I’m in the early stages of parenthood.
I was married at 30 and I fell pregnant within 3 months (planned) and thankfully we managed to squeeze a second one in too.
My husband was absolutely adamant that he did not want any more children after he turned 35 as that was what he classed as being an “old parent” and it wasn’t what he wanted, but thankfully after 11 months of TTC I got pregnant 6 months before his 35th birthday! Thank God.
You may feel like an “older parent” and that’s fine, you are absolutely allowed your own definition as to what is classed as being an “older parent” but you can’t turn the clock back so please try and let go of this regret.
You’ve clearly done very well for yourself professionally so pat yourself on the back for that, and then just focus on your plans for future children without any regrets.