You sound like a very kind, considered, compassionate and thoughtful person, OP, in fact, exactly like the type of person who could make a brilliant adoptive parent. But only if it is the right thing for you and your relationship. And your future happiness.
I’m a single adopter (by choice) so I’ve never had to consider the relationship and infertility stuff. Which, obviously, is massive ‘stuff’.
I’m ten years in with my first and two years in with my second. I’ll be honest and say that it’s the single most best thing I have ever done with my life (I’m a Mum to two gorgeously scrumptious girls) and I’ve lived a lot of life!
But there are still days (many) when I fantasise about getting in my car and driving as far away from my children as I can possibly drive and booking into a hotel room in a remote town, away from the demands of being a parent, and an adoptive parent, to simply enjoy some anonymity and have the chance to rewind my life a little (I have it all planned, where I’d go, what I’d take, what I’d do and how long I’d stay 😀). This is just my safety valve for dealing with the pressures of being a parent to two amazing children who have had a poor start in life and whose behaviour can sometimes reflect that.
But I don’t think I’m any different from (honest) biological parents who sometimes find parenting a strain.
It’s great that you are being so considered and realistic about what you can offer a child rather than expecting a child to fill a void in your life.
Adoption is such a uniquely personal journey, with often uncertain ‘outcomes’, that it’s probably not helpful for any of us here to advise you yay or nay, but I wanted to reassure you that the self-doubt and questioning is totally normal.