Do you live close enough to your home where you can let him out around noon or so and play with him for a bit? I have a 14 week old puppy (got him at 9 weeks) and I too also work. I live about a mile from my work so I keep mine in an ex-pen with a potty pad, his toys and his food and water and Oliver has been just fine! I go everyday at noon and he's gotten used to his schedule and luckily he has much better bladder control now so just try to keep the same schedule daily. He's learned to go on the potty pad (it helps if you keep his ex-pen somewhere that isn't carpeted so he'll learn to go on the potty pad easier) and I keep the tv on for him
My BF thinks I'm silly because I actually leave little kid cartoons on for him as if he is a little toddler!
No worries, your pup will be just fine!!