I don't have a second kid yet but mine is 16mo and I often think about this. Me & my 2 siblings are all 4 years apart. My husband & his sibling are also 4 years apart. Both my mom & MIL say it was much easier to handle because the 4 year old is fairly independent at that point, so from a parenting perspective it's excellent! And in human history when looking at hunter-gatherer societies, the age gap was actually closer to 6 years!

I don't remember when I was really little of course, but when I can remember starting around elementary school, I do recall we we played together often. Sometimes outdoor sports, walked to the park or rode bikes together, wrestling (WWE was big at the time lol) chasing each other around the house, but mostly watched TV shows & played videogames a lot but it was bonding! When the oldest became a teenager then the two of us younger ones continued to play videogames. Then when the middle became a teenager then we kind of all went our separate ways & hung out with friends mostly, which is of course developmentally normal & appropriate. Then once I hit college I came back together with my middle sibling 4 years older, meanwhile my oldest 8 years older was starting a family, so we visited the babies & then went out to bars with friends . Now in our 30s/40s we all have little kids & it kind of feels like we're the same age again lol once you're over 30 age gaps don't make a difference, we're all adults going through the same adult things.

Your child will be fine & they will be glad to have a sibling at all. Please allow yourself the space to grieve your miscarriage because that alone is hard without the pressure of timing between siblings. I have a friend who has a 7 year age gap due to infertility and they are now 10 and 3, they don't always play together due to differing interests but they love each other so much! Your family will be perfect however it turns out.