Hi I Have A Mass On My Palm At The

Hi I have a mass on my palm at the base of my middle finger. I noticed it over a year ago. I was pregnant a few month ago. And now I notice it's bigger. I went to an orthopedic doctor and he took an x ray and he said there's no calcification but he needs an MRI. Until I get the MRI, I can't sleep at night with worry even though he said not to worry. He said it's not a ganglion cyst cause those appear on the wrist not bottom of my middle finer. It's not attached at the tendon, it is firm and mobile. Doesn't hurt unless I push hard on it then it would feel like a bruise. It's sensitive to the touch. It's not visible to the eye but I very to touch it to feel it there.