Regarding your practice and your “roaming” mind, this of course is the experience of everyone when first trying to concentrate. My advice is that you should be less concerned about “concentration” than about purity of “intention”. If one in fact has undertaken a practice in sincerity and with the intention of “serving” God, “loving” God, or “knowing” God, and not with the aim of gaining a reputation for sanctity or of acquiring spiritual “powers” or in some other way of exalting the ego, then that good intention in a way makes up for our shortcomings when our concentration fails. You might want to look again at Chapter 22 of my Advice to the Serious Seeker.

There is also this to be said: the times of “struggle”, when the mind seems the most “out of control”, can be much more spiritually useful in the long term than the times of relative calm and contentment. If we remember to “come back” to our practice each time we find we have wandered, that act itself—the act of return—will help us in time to strengthen our attention. Do not be angry with yourself, or force yourself with anxiety or tension; a simple and gentle return is all that is needed. “My yoke is easy, and my burden is light,” said Christ.