It sounds like your CG is nose heavy. It's usually not too hard to move your battery pack to get the CG where it needs to be. When I was initially trimming my Kaos I put lead in the tail just to figure out where the CG needed to be per the flying tests, then I found the spot where the battery needed to be to get it there lead free and made a hatch for it.

Thrust line is really the simplest thing to check. Go full power and trim for hands off level, the chop the throttle. If the plane keeps flying level for a few seconds before the loss of speed causes it to start going down, you're good. If the plane immediately noses down, you need more downthrust. If it immediately noses up, you need less.