I am very lucky too to have a husband who has even fewer doubts than me!
Like Lorna, when I feel like I'm not doing enough, or I'm not good enough to do this; I look to my husband and he always laughs. We are both products of the GA/US school system (I was average and he was gifted), and we both hated it. Sure, if I had a ton of money I would be tempted (for my oldest) to go to a great private school but those too are few and a killer drive from my home. For the situation you are in, I'm sure your boys are doing great and the experience of living where you do, your travels, will add to their education as much or more so than any private/prep school could.