When you say that you've been "on the fence," I think you need to articulate for yourself (not necessarily here) why you were on the fence. Maybe journaling or talking to a trusted friend who can be neutral but also ask you probing questions could help. Or a therapist, honestly--maybe for both of you, to facilitate this conversation. It's a huge shift to make, and can greatly affect your marriage, depending on what you each decide and how that decision is made.
For me, I've been pretty set on being childfree, my husband is more of a fence sitter, but we've always said if there was a birth control failure, we'd be okay with that. Everyone tells us what great parents we'd be, though I think some of that is just cultural and a thing that people say in our area (midwest) since having kids is the norm.
A child will definitely totally change your life, but if you're a pretty relaxed person and can go with the flow and enjoy it, I think having a kid can be a great adventure--they will surprise, delight, frustrate, engage, etc. as they grow up, and take a huge amount of time and energy, but you get the joy of their presence as long as both you and they exist on this planet (assuming you don't irreparably damage your relationship with them somehow!). How is your relationship with your own parents? How was your childhood? If both of those are good and positive, you likely have a good chance of repeating that success. Even if the answers to those are bad and bad, you can be aware of that and try not to repeat those mistakes. You need to be aware of your own shortcomings because they WILL be tested by being in charge of another human being's care and wellbeing for a number of years (and, as another poster pointed out, that number of years could be the child's whole life if there are medical issues). You also never stop being a parent, even if your kid grows up successfully--you'll likely always want to know they are doing well, want to support them in tough times, etc.
I'd also suggest spending time with kids--either relatives or friends' kids, maybe for an evening of babysitting so you and your wife can get a taste for kids at various ages. Everyone says you feel different about your own kids vs. other people's, but it's a good test of your abilities to at least try changing diapers, run after toddlers, engage with preschoolers, and hang out with school aged kids or teens.