My number 1 rule when flying is to make sure I control anything that is up to me to control. In this case, as an F passenger you can control getting to the gate a few minutes before boarding to ensure you board with F and get a spot in the bins. It may be a couple of rows behind (very unusual if you board with F) but it will be on there. By showing up late you risk that your bag ends up in back or is gate checked.

I'm not saying this was OPs fault. There are tons of reasons why the OP could have showed up late that were unexpected or out of his control but in a normal situation it is in most of our controls. Yes, as an F passenger you would hope that bin space is available or even saved but we all know that doesn't always happen (again, out of our control).