I am sure this is the age old question, but I am struggling with how to balance my full time job and yet wanting to spend more time with my son. I am a single mom by choice...one of THE best decisions I have ever made. I am very fortunate, my son is a happy, healthy almost 4 year old

I have him in a great day care now, but am anxious about when he starts school, how to balance everything.
I can't imagine I am the only one feeling this way. I dread the idea of having him go through his entire school years in after care until 5pm every day. I know a lot of families do it, and kids adjust, but I am struggling since I never had to when I was growing up. I don't want to miss out on his activities in school, but I am far from independently weathly.
I have a very good job, and my career is not that important to me anymore. Yes, I certainly need my job to pay bills, but I don't need to climb the corporate ladder any more. I want to do a good job, but I get so much more enjoyment out of my time with my son.
Anyone else going through this or have gone through it? Any suggestions?