Can we talk bit fit? I'm riding a small filly now, and the bit (myler snaffle) sticks out a half inch (estimating, may be a little less) on both sides. 

I know a bit that is too small pinches, what about one that's too big? I've noticed her crabby (especially going to right side).  Teeth were just done 2 weeks ago when i started seeing some resistance on that side).  Teeth were also done in June before going to colt starter.  

Thinking of going to a side pull or loping hack to see if she has a different response while I find a smaller bit 

Have you tried putting foam bit guards on the bit? That might help. 

I haven't since it isn't a loose ring, but will definitely try. 

when I picked her up from starter, she took the bit fine but was scared when they took the bit out, would throw her head up. If I rest my hand on her poll and move slow, she will drop the bit calmly now, but getting it in, she will barely open her mouth.  I do my very best to go slow and not knock the bit on her teeth, but sometimes happens if she puts her head up or suddenly opens her mouth to accept when she's been fighting it. 

She is sensitive in the face, absolutely hates knotted rope halters etc. 

Have a good massage therapist work on poll, jaw, and TMJ, areas. Not sure about your dentist, but mine used a contraption that jacked up the horses head. Mine always needed adjustments after dental work. 

I haven't had luck with Mylers on small mouthed, thinner tongued horses despite the mouthpiece measurement due to the shape of the mouthpiece alone. 

What did you use?

I have a bunch of snaffles as I used to start a lot of colts,  mostly cutting and cow horse bred.

My go to is a snaffle has a bit thinner mouthpiece than most typical two piece snaffles with a very slight curve to it. Nothing like the Mylers. It also has fixed rings but rather than an offset you usually see, it's a different. (I can send you a pic) Most colts don't take offense to it if they are uncomfortable with a lot of movement in their mouth. It's pretty forgiving and good for starting a colt and using one rein at a time.

Another I try if they aren't happy in the above mentioned is a loose ring ive had for years, the mouthpiece is straight with a lifesaver. The life saver has 3 copper rings on it. Horses that prefer a bit more movement seem to like it best. 

Those are the snaffles I start with and then switch out based on what I feel and need to work on. But if I had to get rid of all my snaffles and narrow it down to a couple for the type of horses I ride, those are the two I'd keep.

Thank you! I'd love to see them 

I'll send you a pm