EGKB
Are you really so insecure?
If you happen to be the proud owner of a Lightning then you can forget pitch to control your speed as you will hit 40K standing on your tail.
If You are the proud owner of a Glider on a still day then only pitch will control your speed.
There is a whole spectrum in between! The less power you have the more pitch becomes the dominant force. The more power you have and the equation balances out.
When the Citation I fly is locked onto the ILS the autopilot using pitch to follow the glide power controls the speed.
As you are flying a Phut Phut Bang trainer with loads of drag and little power where do you think your emphasis should lie especially as you are not experienced and we all do not want you as a hole in the ground?
Pace