I cannot say I'm the most indicated person to help you, but I'll try.
Astral projection is the act of moving your spirit off your body into the astral realm. Yes, there are no physical boundaries there, because through the astral runs energy, different vibrations that the physical realm we inhabit.
If you're having trouble doing it yourself, there are always different ways to do it (such as the rope method, the dot, and so on). And also, there's guided meditations that you can find to help you. I'm not one that ever astral projected, but I try, and results do come, and even if my progress in one attempt was small it gave me determination to continue and do it.
So, this might sound clich, but keep trying . And tell to yourself you can do it, you will do it, and with that with you, I'm sure it will work out much better.