Was it an entity?
 

So,The other day while I was trying to get some sleep, I went through the vibrational stage ( I haven't made a complete astral projection yet) and while this happened I felt warmth from behind me. It really felt like someone was there( I slept on my side). Right after this warmth, the vibrations grew more intense and I immediately woke up.
I don't really remember why I woke up. Actually when I felt this warmth I was pretty calm. I just wanted to know if that was an entity and was it trying to help me complete the separation process?

Hello PencilNotebook, and welcome to the forum.

Was that warmth an entity? Of course I don't know.

But during the process of separation, all sorts of things can be heard/sensed. I recommend reading William Buhlman's book "Adventures Beyond the Body", as he talks about quite a few phenomena which can happen in the "vibrational" stage.
Basically these phenomena can be distracting, and so can any sensation which refers you back to awareness of the physical body. Things like that can abort an OBE qute easily.

For example, some people get a sensation of their heart rate increasing terrifically. This is not the physical heart but an energy vortex. But it can refer them to their body, and so they come back to physical consciousness immediately.

But it IS very interesting, that warmth you felt. It could have been as a result of your own energy rising.
Sometimes, things that happen to us can feel as if they are coming from an external source when they are in fact energies that we aren't used to consciously, which are engineered by the subconscious.