First of all, welcome to the forum Zyr! 
Enjoy your stay 
As far as I know I haven’t had one so far while falling asleep. I think this kind of SP is far more rare than SP when you’re waking up. Probably this SP while falling asleep will be remembered much less because you’re falling asleep instead of waking up.
I’m not sure though but I think you need to shift your point of awareness outside your body to get an OBE, instead of going with the flow. Others can answer this question better than me 
Yes this is the best position to get an OBE, because the so-called “silver cord” (which connects the astral body to the etheric/physical body) is connected to the physical body through the chest, the throat or sometimes through the brow chakra. It’s a good sign that you feel energy flows and vibrations. This means that your energy body is activated and this is absolutely necessary to have good OBEs.
There are various techniques to project if you feel energy flows and are in a trance-like state. For example, shift your point of awareness outside your body. Try to imagine that you’re already floating a few metres above your physical body. Imagine this as vividly as possible and really feel your new environment and how your physical body is trying to pull your astral body back. Really feel this tension. Then feel yourself floating away from your body, through the roof and as far as possible. Feel the wind on your face while you’re flying in unlimited freedom.
Combine this visualisation with the rope-technique (developped by Robert Bruce): imagine that a large rope is hanging right above your chest. Then feel a couple of astral arms pulling your astral body up on that rope. Feel the tension in your astral muscles as you’re climbing up. Shift your point of awareness together with the position of your astral body higher on the rope. Combine the rope-climbing in a harmonic way with your breathing.
Practice these techniques quite often and you’ll get nice results soon. You don’t need SP to do this, but you have to be good relaxed and in a light trance at least. If you don’t feel any energy movements through your body, you first need to stimulate these. The techniques to do this are quite simple and véry effective. You can find them here: astralpulse.com/guides/new/new.htm
Some of the methods are: fly right to the stars with the biggest speed possible and try to believe that you’ll find the astral realms. With a bit of luck you’ll enter the astral realms through plane-like or tube-like structures. Something else you can try when you are lucid: just try and focus back to your body and keep willing yourself to rise and burst out of your body. This may do the trick.
These images and sounds are called hypnagogic hallucinations. These are a great help to do WILD, but therefore you need to passively go with the imagery. Don’t try to actively think about them or they will be gone in a second! Instead, just let yourself flow with them but try to stay conscious. If you succeed, you’ll notice that this imagery will become more vivid and active until you find yourself back in a dream world.
An OBE is a general term for a projection out of body. Most OBE-ers project into the “real-time zone”, an area between the physical and astral world. This zone looks very much alike its physical counterpart, but it may harbor some strange errors and is very much sensitive to thought. Astral projection however is when you project into the astral realms, which absolutely don’t resemble to physical reality. If you find yourself in the real-time zone, you can enter the astral realms by finding anomolies, like unknown doors. Imagine that these doors are the gates to the astral realm when you open them. Mostly you’ll only find other doors, but keep opening them until you’re in the astral realms.
Beyond the astral realms, there are still higher planes. The higher they are, the more complex and abstract they are. These are called mental, buddhic, atmic, anupadaka and adi planes, beyond astral projection there’s mental projection, buddhic projection and so on… These higher planes however are very difficult to enter.
Reality checks are a good technique. You can find part II of the big reality check topic here: https://community.ld4all.com/t/the-big-reality-check-topic-part-ii/7108
Other good techniques are MILD, WBTB, Suneye. Use the “search” option on this forum to find the various topics about these techniques.
Hope this helps a bit Good luck!