This isn't at you personally but I think it's a no win situation. Once you tell people you are ttc I find it odd that people then get upset about being asked about being pregnant. I figure you only tell your close friends that you are ttc so why not then tell them, even before 12 wks, regardless of what happens they will support you. It's like opening the door then shutting it in their face. Similarly I would imagine people would be upset if it was known you were ttc but no one asked how it was going, they could be accused of not showing enough interest.
It doesn't sound like they are being nosey, probably think they are doing the right thing by asking. Anyway not a go at you, just my observations from being faced with it irl.