Sadly in the same your situation : 3500 jet hrs,I have applied almost
everywhere and 0 invitation!!!
You are not going to get one as long as there are kids willing to pay for their own training and accepting sub standard conditions.
That is not going to change unless either the airlines change their policy, and that is not going to happen as long as the beancounters are in charge, or you need the existing crews putting a stop to it, and that is not going to happen either, too many of them are complicit in this practise.
You just wait till this current batch migrates to the LHS and accepts huge paycuts to do so, that will only accelerate the downward spiral. By the time that happens it will be too late for the exisiting senior crew to do anything about it, and all of them will come in here complaining how crap the industry has become.