Too young?

I had my son when I was 18 (two months away from 19) and he was definitely a surprise for my SO and I. But now we’re talking about when we plan to have more and we would like them to be sort of close in age. So we planned for when he is 4 to start trying. Then I thought about it and i’ll still only be 22/23 years old. I just feel like that’s too young to have two kids or that people might think that. My family keeps saying not for another 8-10 years but I don’t want my kids growing up too far away from each other! Anyone else experience this of had kids this young how did you do it? Would you change the difference in age?