Congratulations! I'm so excited for you. I just have to tell you, enjoy every moment. That is my piece of advice for every new mom. You only get all these firsts once. Get as much sleep as you can now and let people wait on you because next time they won't lol. No seriously, enjoy it. I miss it so much and would love another but after this week, I'm ready to send my hubby to get snipped. Trust me, I wouldn't have to push him either hehehe.
BTW, I have a friend that this happened to. She had female surgery and they told her there was no way she could get pregnant that month but she did. It does seem when you aren't trying is when it really happens. Congratultions again! Keep us posted. You'll love being a mom.