Feeling guilty

Ok so I have a now 3 year old and I’m feeling guilty that she’s still the only child because everybody tells me to have another one to have them close together and so they can play but my thing is that I’m still young and have a lot of time but I do feel guilty at times seeing her play by herself and just wanna know am I wrong ?? Should I wait or should I just go ahead and try for another. And btw I’m financially stable , married and everything’s good just feel like I’m not prepared for 2 babies but Idk help please!