I find that with everything else being equal, the height of the strings is important. My Serenade was a little lower than my teacher’s Prelude, and I place it on a box about 4″ high when I practice, then I have no problem.
You might want to try breathing when you’re not focused on
Is there any way to play your harp for an experienced harpist? It’s difficult to attempt to answer your question not being able to see the situation. It is likewise difficult for the player to know what is wrong since they can’t see their own form. Have real life feedback from an experienced teacher and/or performer is the quickest path to the right information. :o)
Wow, I read this before, but just recently have had the same symptoms crop up. I find that when I am reaching for the lowest strings (something that I am doing a LOT lately since my harp has more strings than anyone elses in our ensemble) I catch myself hunching over, leaning forward and holding the harp against me with my right hand. If I don’t hold on, I will push the harp away from me with my chest. I have very short arms and don’t have a problem reaching for the occasional low C, but in one piece we are doing all my notes are in my lowest octave. I made a comment once that I didn’t know when I got a bigger harp I would end up playing string bass! I have been trying to sit a bit higher than I am used to doing (short arms, short legs) and that helps some. I also find that whenever I take a break, it helps to do shoulder rolls.