Sorry for the late reply, I haven't been on here in almost 2 years.
Anyway, what brought me to this site was originally a lingering fear about having lymphoma, specifically follicular lymphoma (a non-hodgkin variant that rarely affects people under the age of 45... I'm now 27). I thought I had this because I was also concerned about a small palpable lymph node in my groin on right side. Now, as far as I know, there is no difference diagnostically whether or not the node is palpable on the left or right side, but I can tell you that I WAS NOT diagnosed with lymphoma.
I noticed the node almost 3 years ago, and being a lifelong hypochondriac, I gradually went from "who cares" to complete panic. I visited multiple doctors probably over a dozen times, had blood tests and ultrasounds done, over the period of about 5 or 6 months... all the while trying to complete my MA (which I didn't, largely because my anxiety spiralled out of control). Needless to say, all of my tests came back completely normal and no diagnosis was made, not that that meant anything to me at the time, as I always figured out how to find holes or mistakes in the tests that made them "incorrect."
So, try to be calm about this, it's probably nothing, as most lymph nodes that do not become "clinically enlarged" (meaning a significant sign of swelling, which would be larger than the 1cm you described) become palpable over a multitude of benign reasons and are rarely indicative of malignancies.
Just so you know, my node is "semi-hard" as you describe (hard, but not like a bone or a "rock"), roughly 1cm, and not very mobile. It's still palpable to this day, 3 years after I was convinced I had lymphoma.
From what I can tell, mobile just means what it sounds like, that the node would be able to move or "slide" around under the skin when you apply pressure to it. That being said, even though I know you've probably come across multiple medical journals or "self-diagnosis" sites that list hardness and lack of mobility as a warning sign, however there are other variables that go into diagnosing a condition, not just characteristics of a lymph node. A close friend of mine just graduated from med school last year, and he was saying that being an effective diagnostician is recognizing patterns of symptoms, not necessarily in isolation. It is really is an artform in many ways, and impossible for the untrained and unexperienced, like us hypochondriacs, to do to ourselves.
Hope this helps.