Sounds like you are moving through spiritual awakening. Congrats!
“In the oldest texts of Buddhism, dhyāna (Sanskrit) or jhāna (Pali) is the training of the mind, commonly translated as meditation, to withdraw the mind from the automatic responses to sense-impressions, and leading to a "state of perfect equanimity and awareness.”
I don’t know if it’s perfect exactly but the whole training the mind to reduce automatic responses to sense impressions sounds exactly right to me.
I still have some difficulty controlling it but it gets better every day. It seems that the more I dare myself and confront my fears, the better I get at self regulating my emotions.
And damn do I wish there was science to this, because I was very committed to a scientific viewpoint before this happened, which is rather inconvenient at the moment, because my only source of information about what I’m currently experiencing is religion.
Now, ten years later, I feel much further away from it than I have before. However, your experience isn't the first I've read where breathwork allows you to control mental "elevation" (for lack of a better phrase) at will -- it makes sense, given the way that breathing integrates into the mind/body connection.
I think the book Waking Up by Sam Harris gave me what I needed to take a step in trusting my own subjective experience. And realizing that there is knowledge and wisdom that science has not enveloped. And that that is okay--it doesn't mean it's out of reach for science, just not there yet.
My two cents.