So Close to O.B.E., But cannot get out?

Over the past few monthes, i have been studying lucid dreaming, and astral projection. I have learned much and many teqniques to having an o.b.e. until i found one that works well..
But, this happened 3 times in the past few weeks, and is the closest i have been to having an OBE, but i reach the final stage, but nothing. here's what happens: after in concious trance, it gets hard to breath, (i do not panic), Heavy vibrations, i cant really hear, etc, but i try to immagine (using the rope teqnique) that i am climbing the rope, as i climb it gets heavier to breath and heavier vibrations, finally, all stops, but i feel the same, i try to get up, try many reality checks just to see that i am still in my physical body.. what does this mean? i have read that it is maybe due to fear, which cannot be true, i know that in NO WAY Possible that lucid dreaming/astral can harm you in Any way besides temporary fear, and i have no fear before i try to astral project.. what is this? how can i finally get passed the vibrations & breathing, and get out of my body? Please, i need a obe expert on this :/

*And to note, i have never succesfully astral projected before, and those 3 times were the closest. But however i have had quite some lucid dreams, (never any fearful ones)*