For FMQ use the same thread, top and bobbin. It sounds like something was up with your top thread either not being threaded correctly or the tension being off. Birdsnesting often happens due to the top thread having issues. Nothing wrong with using a polyester thread to quilt with or even rayon. I've used both with good results. I set up a new way for my thread to feed into my machine from the cones that they come from and it likes it MUCH better.



The thread spool sits on the table, goes up to the thread holder "arm", through the safety pin eye hole and then it is threaded into the machine like normal. This gives the thread time to unwind a bit after coming off the spool and it pulls cleanly off of it when sewing at high speeds (while FMQ or doing machine embroidery which is typically when something will snag and break your thread).

You may want to try something like an Aurifil 40 wt. cotton mako thread and see how your machine does with FMQ.