Does ...b5 give Black an advantage? After being squeezed for an entire game I got the chance to ease my position with a pawn exchange. Incidentally, this would open lines for my pieces to attack opponent's weakened king. I played ...b6-b5 in the position below, and won. Computer played badly so I ask here for help to determine objective assessment of the below position -> does ...b6-b5 give equality for Black or can he aim for more?

[Title "Black to move"]
[fen "2r3k1/p4p1p/qp2p1p1/4Q3/2PR1P2/P7/1P4PP/7K b - - 0 1"]

1...b5


EDIT:

To help the viewers understand the nature of this question, here are the lines I saw that convinced me that Black suddenly gets good chances after ...b5 :

[Title "Black to move"]
[fen "2r3k1/p4p1p/qp2p1p1/4Q3/2PR1P2/P7/1P4PP/7K b - - 0 1"]

1...b5 2.c5 (2.Rd7 (2.cxb5? Rc1+) 2...bxc4 3.Qf6 Rf8 4.Qe7 {Trying to win back the pawn} c3! {With the threat of Qf1 checkmate, and cxb2 Black should win in my opinion} ) 2...b4! {Threatening Qf1 checkmate} 3.Qe3 $8 bxa3 4.bxa3 $8 (4.Qxa3? Qf1$) 4...Qf1 5.Qg1 Qxg1+ 6.Kxg1 Rxc5


I think 2.Rd6 was played in the game but I can't remember what happened nor what I had in mind as a response... Since it is clear that after that move Black must defend, my question is answered -> Black can not aim for more than an equality :(
Rd6 followed up with 3. c5 looks strong for White, unless I am missing some obvious tactics.