When I read the title of this thread, I thought "here we go again, another 200hour pilot, fresh licence, and why won't the airlines recruit me?" So it was refreshing to see that wasn't the case.
For what it is worth, you have actually done well, and made some timely decisions. The frustration now is how do you make the jump on to the next stepping stone having done four years on the first one?
There are a few regulars on these forum that work for operators who put a great deal of store on people such as yourself, that have put the time in working their way up. Unfortunetaly, they are few and far between, but I am hoping Mad Jock (somebody I often disagree with) will put in a contribution, because I think this is a subject he would be able to help you with? The problem as always is the simple dearth of opportunities out there. All you can do is "network" hard, and pursue every lead that comes up. I know it is cliche, but it often works.
Getting the maths to add up can be a predicament at any level. You only have to read some of the other threads on this and the terms & endearment forum to realize that brutal truth.
A general job within an airline might well help you network, but I wouldn't give up the instructing job if at all possible. As difficult as it may be, it keeps the currency going and the experience building. If your current position allows you to build multi-engine experience, then try and do this. As bad as the maths might be, in your current role somebody else is paying for your experience. Without it, you are.
You are not in a bad place, even though it is a very difficult job market.
Good luck.