Snovid, one way of looking at it is that these are just dreams...Other, that these dreams are signs of purification. The "cave" is well known symbol of subconscious, so if you have these repetitive dreams in a cave that might indicate that your karma (subconscious mind ) is purified. or rather that the practice is penetreting depths oh your unconcious, if you like... As you well know there are fantastic books in Polish about Dream yoga that you can read, Namkhai Norbu`s and Tenzin Wangyal`s as well. Soon Charlie Morley`s book "Dreams of Awakening" will also be published in Polish as I`ve learn from his FB page.
Nevertheless, If you are struggling with your unconscious, as you are, you might like to consider, if you will, some psychotherapy first, before you seriously engage yourself in deep practices as Dream Yoga.
Also, I have a very deep and strong intuition, that it would be immensely beneficial for you, to stick to one particular school and one teacher, and just follow his or her advice, rather than mix all things from all schools. There are lots and lots of Buddhist Centers in Poland - Kagyu, Dzogchen Community , Bon, Gelugpa and so on...Just choose one, chose your teacher and follow...If there is a requirement to do Ngondro, then just do it. You know, If you want, you can write to me a private message in Polish. Good Luck