So after quitting Physio I had to make up a new routine. The breast care excercises are for me useless. So what I do is lie on my back take the matechtomy side arm, my right arm , with my lefth and. ...
It is great to hear you have found ways to support your recovery, it is disappointing that you had to discover this on your own.
It is really positive that you are seeing good results and seeing improvements in daily activities too.
I found an exercise similar to what you described (see below), when doing some research on supported exercises. Utilising the wand(bar) may make it more comfortable for you, rather than having to reach across with your left arm.
This exercise helps increase the ability to move your shoulders forward. You will need a broom handle, yardstick, dowel, or other stick-like object to use as the wand in this exercise.
Hold the wand across your belly in both hands with your palms facing up.
Lift the wand up over your head as far as you can. Use your unaffected arm to help lift the wand until you feel a stretch in your affected arm.