Felicia, I have a similar issue. My arms create a "Y" shape , so it puts too much strain on the joints of my elbows, wrists, and shoulders. I also tend to use my biceps more than I have to. I have to modify just about every move out there.
I talked to a physiotherapist and she gave me two things to try.
The first is kind of similar to the inward/outward motions that you tried, but it is more of a shift in the hand placement to change how the weight is distributed. Hope I can explain this properly. Get on all fours. Place your palms flat on the floor, then lean your weight into the hands. You should feel the weight distributed across the base/meat of your hand. Now, without moving your hand's placement, shift/pivot the weight more towards the base of your thumb, just under your wrist. You should feel a difference in the elbow and shoulder and wrist.
The next one might be difficult to explain, as it is more of a mental shift, and requires you to have an open mind about how positive energy/flow can affect your body. Get a partner and stand face to face. Place your hand on their shoulder, arm straight but not locked. Flip your arm so the palm is facing up. Have them GENTLY pull down on your arm at the crook of the elbow, while you resist. We tend to use our biceps when we resist. Now comes the tricky part. Stand in the same starting position. Close your eyes. Envision positive energy flowing from your shoulder, down your arm, and straight out beyond your fingertips. Then ask your partner to again, gently pull down while you resist. See if you feel any difference. This may take some practice and handstands would be a perfect exercise for this. The first tim eI did this I was amazed at how much more solid my arm was and she was not able to bend my arm like the first time.
Hope these tips help. Good Luck!