It sounds like your 3 month old is sleeping like a champ. What's the problem? All children have different sleep patterns. If your baby seems to be happy and thriving on a couple of catnaps and then one long nap, I really don;t see a problem at all, just because it's different from what your first did. It sounds like the baby gets plenty of deep sleep if he sleeps all through the night plus a 3 hour nap. Really, don;t worry. And I wouldn;t try to schedule your baby too much. Let him nap when he's tired, not when you want him to. Napping starts to regulate itself more naturally anyway around 6 months or after. Be thankful for what you have. You'll figure out how to "get things done" - you just have to shift your thinking as to what is possible to get done with two now. It's more challenging than with one, and yes, your house will be a little messier, and you will probably find that you;re doing more chores at night after they go to bed than you did before, but that's just how it is.
I have to say I only wish I were in your situation- my second is still not sleeping through the night at 19 months and my first has not napped at all in a year. So be happy, believe me, be happy.