Well firstly congratulations!

Secondly,
I hate it when people offer unwanted opinions. Way too many people do this, especially in regards to others' parenting, in my opinion!!

I have four kids.. None of them were specifically planned.
My second one was a big shock. She is only 13 months younger than the first - I got pg when baby #1 was only 5 months old. I would NEVER say she was a mistake. She wasn't. I was never unhappy about her. I do, however, tell people she was a 'surprise' and a nice one at that! She is so perfect.

Anyway, maybe if you tell people that you were waiting to get PG but not actively over trying but at the same time tell them how excited you both are to be pregnant, they may get the clue? I'm sorry you are dealing with such negative responses at a time that should be so happy for you!