That is exactly what happened to my wife and I when we started about three weeks ago. We thought we were doing fine estimating "by eyeball", but we weren't making a lot of progress.

I found a great PDA diet diary and carb database that allows us to keep a very accurate count of what we eat. It's a bit of a pain adding up all the fiddly bits in a meal, but the peace of mind of knowing EXACTLY where we are is a boon.

(and we now consider ourselves to have TRULY started induction eight days ago... ) I figure we were actually eating 30g+ per day just "winging it".