It's your body; it's your peace of mind.
So, if you're thinking along the line of having a biopsy... there's no real need to "push."
Just tell your doctor(s) that you'd prefer to have the lump biopsied even though the diagnostic test results suggest that there's nothing to be overly concerned about.
You do have a choice in all of this.
Good luck in whatever you decide.
Welcome to Medhelp and to the BC Community.
If your lump is not picked up by mammogram or US, another option might be an MRI, whick is more sensitive and can detect things better in young and/or dense breast tissue.
Because it is highly sensitive, it can produce false positives, but this would presumably not be as much of a concern in your case since you apparently have a palpable lump.
If indicated, once located by the MRI , the lump could be biopsied.
If the itchy patch persists, you could have it examined by a dermatologist or breast specialist, and if suspicious, a biopsy could also be done on it.
Hope this gives you ideas for some options, in case you run into the scenario you mentioned.
Best wishes, and please let us know how things turn out...