If it was me, I'd start from the beginning. Getting proper arrow tune is the most important aspect of archery. Get a bare shaft and test for spine. If your spine is way off, you can tune until the cows come home, and you'll never get a good flying broadhead. After you have the spine adjusted - by changing tip weight, shortening the arrow or changing draw weight, you can also check nock height with the bareshaft test.

After you're done with the bareshaft testing, then walk-back tune the bow. Go back to at least 60 yards to get windage set accurately.

General keys to good broadhead flight are:

High FOC %. I recommend an FOC of at least 12%, especially for anyone who isn't very good at tuning and arrow. Higher is even better.

The fletching should be feathers attached with a helical twist. It is very important to get adequate drag on the rear of the arrow and to have the arrow spinning. Feathers are very good at this, plus they reduce the weight at the rear, which is also a good thing.

Arrows that are straight with broadheads that are attached perfectly straight. This is fairly easy to test at most archery shops.

Spine tuning: Very beneficial if you have the equipment to do it.

Don't worry for one second about what any of this does to arrow speed. It has no importance. All you should be concerned with, is getting your broadheads flying properly. If you do all this properly, your broadheads will hit very close to your field tips, even in breezy conditions.