ANA titres can vary by at least a factor of two, both for the same person tested in different labs and for the same person tested by the same lab.

This is because the test entails setting up a binary dilution of a serum sample. Maybe on one day an elevated titre of ANA in one person tested in one lab might be at a 1:160 dilution and the next day it might be at a 1:320 dilution for the same person tested in the same lab.

Your titres are slightly elevated but many people have titres in that range with no other signs of an auto-immune disease.

A homogeneous staining pattern can but need not indicate SLE and/or Mixed Connective Tissue Disease but usually more investigations are needed before/if a diagnosis is confirmed.

This information might help you RACGP - Antinuclear antibody test.