I think living a full life can be done no matter what. You just have to figure out what kind of life you want to live and if that involves having someone then do it, if it involved having kids, then do it, if not don't. Marriage and kids are not requirements for a full life, living the life you want to is, imo. The problem/issue is figuring out if marriage, kids, etc. is what you want because they are not the easiest to get out of if you find that they aren't what you wanted, especially kids. Those things aren't wedding gifts you can return for store credit.
And if someone (in this case SD) is asking for advice about kids (whether to have them) imo it's important to paint the entire picture and in doing so, you're not a terrible person for admitting that kids aren't super awesome all the time. This point seems obvious, because what is super awesome all the time? but the things we might hold dear as parents or hold meaningful as parents or are fun as parents may not be things that we (a) held as meaningful or dear before we had kids and (b) may not be things that others find value or fun in or could eventually find value or fun in. It's important to lay it all out there as the expereinces we have had, and then let SD decide (not that he's going to decide based on us jackasses). Or we could just say "it's awesome".