I'm wondering if I would be better off switching to some other kind of retirement plan. Thank you.
There are a lot of questions that come to mind. I will assume you have access to a 403(b) and National Life Group is one of them. National Life ratings can be found here:
I would also look over the following sites from the OK Teachers Retirement System...
...and see if this answers some of your questions about what options you have access to if you are concerned about National Life versus the other options you have available.