Dear L:
I meant to quote you and by mistake edited your post. You will find your questions in quotations. Sorry about that.

I am definitely NOT astral.
I'm not sure what you mean by this, but everyone has an astral double. So you are physical and astral, and everything in between.

However, back in October 2008 I was lying on my stomach on my bed watching TV and all of a sudden I felt an invisible figure land behind me, he started to [removed unnecessary content], then had int*rcourse and then [removed unnecessary details.]. Can an Astral have sex with a non-astral.
This post reminds me of someone else. Have you posted here before?
Anyway, chances are you were in trance, and experienced your thoughts in an objective way, as in the hypnagogic state. This is not uncommon.

IT also happened quite a few times after that as well.

Also sometimes I feel someone getting into bed with me, touching me.

This kind of started when I was fantasizing about a exboyfriend, my male ex-bosses and one of my male cousins.
You probably are separating and enacting your fantasies without realizing that's what you're doing- with your own energy body, also known as astral feedback, which accounts for many of what are known as 'dweller' experiences.

There is a chance that your fantasizing in trance attracted a succubus, but I'd only suggest this if:
You orgasmed, and
You felt very crappy afterwards, exhausted for the rest of the day or the next day if it happened at night.

If you felt fine afterwards, chances are it was only astral feedback- this means that you're probably a spontaneous projector.

All of the terms I used are in the AD Pedia (in my sig) if you have any doubts.