The transition to two kids HELP

So I've recently found out I'm pregnant, I already have a little boy who is three in January, he will be exactly 3 and a half when this baby makes it arrival, I struggle with him sometimes, hes such a good boy but i have an illness that holds me back sometimes. Now I'm pregnant and I'm terrified, I'm excited deep down but all I keep thinking it the transition to two kids, please tell me it's not as bad as I'm thinking 😩 I'm also very outgoing so I'm having to put my life on hold which is fine, its selfish to see it like that but I was just starting to have abit of freedom again