It’s normal and common for people to want more children than one. I am glad I am not the only child. My brother and I have each other back and are there for each other in good and bad. Siblings bond is important to a lot of people. In addition mine and his kids are very close. My daughter and his oldest son are as close as siblings, not as much as cousins. These things are important

I am sorry you two have bad relationship with your siblings. But it’s not any kind of set in stone rule that that’s how your kids will grow up. I ended up only having one child because I couldn’t no more and life just played out that way but thankfully my daughter isn’t the only child as her dad has more children whom she is very close to. Of course it’s ok to have one child but most people want their kids to have a sibling

Having said that, your wife seems to be rushing into it. Maybe she could explain to you better. Does she want kids be close in age, does she worry she is getting older, does she worry that’s the only chance. And I also wonder if two of you not discuss number of kids prior to the wedding? Often these things are discussed and aren’t a surprise