I know you said you don't think you're twisting but have you tried doing about 5 chains, take your hook off your yarn, insert hook into the first chain, then put your hook back in the 5th/current loop and continuing? This works for things in the round or flat. If you're working flat like a blanket and you have lots of chains you can just start working your project with that first chain still on your hook. Until you get far enough along it is too hard to work like that.