Mully, you aren't too old at all, but i won't lie and say it is an "easy" age to have children. (at least in my case, cuz having the son beg for me to go out and play catch or give him batting practice last summer after a HOT day of loading airplanes brought out aches that i never dreamed could have existed.

) right now, he's 11 and i'm 47.
Now look at it for the sake of your current son. Being an only child has it's ups and downs. I am an only child and where it wasn't that bad as a kid, since there were cousins living here quite often, it is starting to take it's toll in recent years.
We were still living in Minnesota when my mother was dying of cancer, and i needed to come down here to care for her on weekends during the school year, and go back up to MN on weekends during the summer for my ex to have the kids. Drove 22 round trips with a 5 and 7 yr. old doing the "he looked at me", "she touched me" routine in the back seat!!!
Now we have moved back to Iowa since my father has no business living alone. I feel guilty getting away for a couple days occasionally for pleasure, but sometimes it just has to be done. The weekend before the superbowl party this year, he had his old pacemaker/defib removed and replaced to the other side due to device infection, the weekend after the superbowl party he went into cardiac arrest again for the 4th time in 2 years, and last week he fell on the ice and broke his elbow.
trying to juggle his schedule, and the schedules of a 14 and 11 yr old is extremely difficult. i won't call it a burden, but it sure would be easier if i had any brothers or sisters to help part of the time when i can't be around.
Reference Taoist's "pic of the day" thread as i say.......GO FOR IT.
(another added note about being away from dad... the kids and i got trapped over at the Moline Holiday Inn over the ice storm last weekend while attending a family reunion, and dad had to fend for himself at the house with his new cast...i felt SOOOO guilty over that one. DAMN LUCKILY we never did lose power at the house, even tho a branch landed on the power line in the back yard, and we were only without power for 6 hours at the hotel.....had to suck being you with the length of time you were powerless.

)