NAAM, I have ten nephews and nieces too - soon to be eleven, god help my large and overly fertile family! (In fairness I have 5 brothers and sisters, so we are not Mormon-stylee or anything like that).
Some of them are monstrous, and some of them are sweet, most of them are a generous mixture of both and all of them are exhausting and time-consuming - I love them all, but as colditz says, it's nothing compared to the love you feel for your own child. I can only describe it as the purest and completest sense of love I can ever imagine feeling, and despite all the nightmarishness of being a parent, I feel immensely privileged to have the opportunity to experience that emotion.
Do I think a life without children is wasted? Absolutely not. On this site you are always going to get a biased view of parenthood, it's like going on a Christian website and saying "is being a Christian any good?" It's what we all are, it's what unites us and, by and large, yes we all think it is good! But your reaction to the idea of your dp being a godparent says quite clearly - as others have said and I think you know - that you are not [yet?] reconciled to never having your own child.
The thing is, you can't imagine life with a child until you have one. And then you can't imagine life without one. So saying "can you imagine life without your dp" is a meaningless comparison, to be honest. You can only go with instinct, no-one can adequately describe what being a parent is like to you.
Funnily (or not) my BIL could be your dp, he is a similar age with a similar-aged dd who he has never been allowed to have contact with (nightmares with ex-wife). His dp is about 34 and starting to get broody; I really feel for her as he is 100% committed to not having another child, because he can't bear the heartache of losing another to a vindictive ex. I have no idea if that's part of your dp's motivation, and it doesn't really matter, I could not live with that; deciding together not to have kids is one thing, but him saying it's alright for him to have one but not you, I couldn't handle it.
In honesty I think this is going to be one of the key moments in your relationship with dp. 34 is a dodgy age to be contemplating starting again (I'm 34!) but you do have some years of potential fertility ahead of you, and I feel you may end up wondering if the next 10 years are best spent giving those away for this man.