While I am glad you apparently got to the 4th jhana a few times; nonetheless, we have already established your meditation teacher doesn't know anything about samadhi. So, since mirror gazing has helped you, then keep it going, but keep in mind there are other important stages of meditation necessary to attend to, such as:
1) First stage of depth arises when during meditation we find comfort in the practice of meditation, then we allow ourselves to relax, submit, let go deeply, and we find comfort and refuge in that sense of relaxation.
2) The second stage of samadhi is the stilling of the mind. When the mind is still it is no longer involved in any kind of cognitive activity such as: memory, speaking, visualization, repetition; and all we are doing is observing.
3) The third stage of samadhi arises when we feel comfort and relaxed, and our mind is still, then various charismatic phenomena arises, which are often referred to as energy, which often manifests as: aura, chakras, etc.
4) The fourth stage of samadhi is associated with a sense of timelessness in which we feel so free of discomfort that we feel that we could sit in meditation enjoying the comfort, relaxation and stillness as if we could sit there for ever, and we do. We only realize afterwards when we look at the time and find an hour went by but we feel like it was only minutes.
5) The next phenomena doesn't have a recognized stage, but we probably should give it one. Here the contemplative will experience a number of phenomena such as: an apparition of an anthropomorph sitting before one. This apparition is often believed to be a saintly person such as Jesus or Shiva, or Babaji, depending upon one's cultural context, but we have found it is one's own body being observed by one as one is leaving the body. This apparition often gives way to a luminous sphere which is called 'kasina' in Buddhism and other cultures. It is often believed to be a nonphysical being, but it actually a portal to the immaterial domains whereby one can launch out of the body and away from the material domains into any place, time or dimension.
The remaining 4 stages are all out-of-body and are so abstract and beyond most people's context that it is irrelevant to discuss until it happens.