time management

***Please let me know if you have any ideas or experience that may help me.*** - - I am blessed to work from home and be able to stay home with my 20 month old son. I have a schedule that I am to work 4 hours between 8am and 5pm and then an additional 2 hours or more after 5pm. I am very thankful for my job and the flexibility. However I have started to feel guilty that although I am home with our son he does not always have my full attention. This is what our day looks like now. Wake up 7:30 snuggle and watch a few minutes of a show then change diaper and have breakfast. I try to work for 1 hour at this time in our day while interacting with him during breakfast and then he plays for the rest of the hour. This time consists of him bringing me toys to play with and he plays trucks on the floor near me or even types on his keyboard next to me. Then we go outside or have a play date or run errands. Lunch is between 11 and 11:30 then its nap time. He usually sleeps 2 hours and I work as much as I can. So I have completed 3 hours of my 4 hours. This is where I feel bad once he gets up from his nap we usually play or do some sort of an activity. Then at 3:30 or 4pm I set him up to watch a show sometimes he sits through 15 - 20 minutes other times he just gets right up and plays. I am looking for suggestions on how to entertain him for 1 - 2 hours during the day while I work. I understand children watch TV and it isnt the end of the world for him to watch tv but is there something else I could be doing? And the TV doesnt hold his interest. I have searched the internet and mostly found things like playing blocks, puzzles, coloring. Does anyone know of any websites that have preschool lesson plans for free? Do you think that would work with a 20 month old? Let me know what you think!! Thanks!