Everybody has their limits. All we can do is work within them. I mean for real I can't play a regular c chord, or b minor,
the list goes on and on.
Allow me to offer you a tip in the area of the Bm, Paul.
Start by playing the standard open Am, but with your 2nd, 3rd & 4th fingers for awhile, instead of your usual "proper" way. Then you simply slide it all up 2 frets & bar the 2nd fret. Voila! Even should you miss the mark with the bar if you don't have the hand strength to pull it off, you'll get the necessary F#, B, & D notes that make up a Bm chord, & your failed bar will only deaden the rest of the strings. Once you have memorized the location, you will always be able to pull off a three-note Bm at the very least, this way. (move those three fingers up one string & you have an F# major, which is also very easy, now!)
Open C is a prob for many ppl, (me, too, these days with my numbish fingers!) & the only suggestion I can give you is to constantly strive to arch the fingers high & play on the very tips.
Good luck.


