No: the portal takes things to, not from, the Astral Plane
The rules on putting bags of holding into each other state the following (DMB p. 154, bold added)
Placing a bag of holding inside an extradimensional space created by a Heward's handyhaversack, portable hole, or similar item [e.g. another bag of holding] instantly destroys both items and opens a gate to the Astral Plane. The gate originates where the one item was placed inside the other. Any creature within 10 feet of the gate is sucked through it to a random location on the Astral Plane. The gate then closes. The gate is one-way only and can't be reopened.
The rules do not say that it opens a portal "between the Material Plane and the Astral Plane", or similar wording. The portal opens only to the Astral Plane, regardless of the plane you are on when you place the bags within each other.
The fact that the portal is one way only is crucial as well. Even you were in the Astral Plane and someone on your home plane attempted to put two Bags of Holding inside each other (still on your home plane) hoping to open a portal you could travel through to come home, they would be unsuccessful. The portal only takes things to the Astral Plane: it doesn't provide travel from it.
If you were to place two Bags of Holding inside each other while on the Astral Plane, the portal that opened would then deposit you in "a random location on the Astral Plane." At most, you'd move to a different part of the Astral Plane: you wouldn't get an opportunity to escape it.