If your actual DLI is 29 now and you can raise it to 33-34, that should help your plants some. Not hugely, but definitely in the right direction, provided that your other factors are in line. Cannabis can handle up to ~60 or so, so whether or not your app is super accurate, you are almost certainly still in the range where more is better.
You are nowhere near the point where fiddling with CO2 will help. In any case, unless your tent/lung room is tightly sealed, adding CO2 does not work well anyway.
Good luck with it.