dear against gravity
twice you have said you use 70 MPH...doyou have an old plane with miles per hour on the air speed indicator or are you mistaken?
we use KNOTS (nautical miles per hour).
have you looked up the published speeds in your pilot opearting handbook? have you ever actually done a weight and balance and then checked the exact speed you should use with full flaps on final?
you speak of stretching the glide...well that is good to know...but as long as you have engine power available you aren't really gliding so much as making a power on approach and landing.
yes, constantly look for a place to land IN AN EMERGENCY...I even do that in the jet...but try a very long final...at least three miles started from 1000' on VASI/PAPI fully configured for landing at the published speed...not faster.
if you get low and slow add power (its no sin to add power...even max power))
high and fast reduce power.
don't be afraid to go around.
but I don't know why you are changing speed on final unless you are accomadating trailing traffic. you are just learning and stable approaches at the right speed are vital.