finger flexibility

I am a 40+ year old female and taking cello lessons.  I have small hands and having difficulty getting my left hand fingers to bend and spread apart to match the note intervals.  I'm already using a smaller (3/4 size) cello to reduce the distance.  The problem is my 2 middle fingers, when bent in position, do not want to separate the approx. 1 1/4" distance, but prefer to stay close to each other. Is there anything I can do to increase their ability to spread apart (and stay there!)?  I do some basic hand and finger stretches, but after a year there is not much difference.  Thanks for any advice.

[Suri123]

Hi, since you have to be physically examined, i think you better consult a orthopedician who can examine you and advise you.Physiotherapy can be of some help to increase the degree of mobility, still meet a orthopedician.