Only child

I have a son who is 4 and will be 5 in April. I have always felt so guilty that he has been an only child and never has other kids to play with or learn with. I always pressure myself to occupy him because I feel guilty when he is just sitting there by himself. I wanted to have another child when he was around 1 or 2 at the oldest but my husband wasn’t ready to have another because he already had two kids when we met. I am currently 8 weeks pregnant am I am so happy and thankful. But I still find myself carrying this guilt that my son will be 5 when the baby is born and may not have a bond with him/her because of their age difference. Idk if it is normal to feel this way but I just feel bad that he hasn’t had another child closer to his age to grow and bond with through his baby/toddler years. Has anyone else ever felt this way?