You did not give the power of right eye.You said Contacts are of the same power as of glasses.
But,usually in high myopia
Contacts will be having less Power than the glasses.So,Check the power of the contacts again.If the power of right eye is more than left eye,the vision will be little less in right eye due to high power.
Check your Retina
regularly with Retinal specialist so that weak areas can be detected early.
of the eye will be loose and can be moved.The membrane in the left eye is nothing but conjunctiva.
Do not worry.
Wish you good health