This problem is sometimes caused by the US habit of giving a carb content figure including fibre, from which you need to subtract the fibre amount, giving a "net carb" result.
In the UK fibre and carb is counted separately - so your pecans are 7.2g carb PLUS 8.6 g fibre. The fibre does not get digested to glucose. It doesn't (unfortunately) cancel out any of the carb, so you're effectively eating a food with 7.2% carb - or eat 100g of pecans, you've eaten 7g carb.
Does that explain it?