It's hard to judge others' motives, and hard to judge our own. Our own minds are not transparent to us.
However, here's a decent test to determine whether you might be solely or predominantly virtue-signaling. When you express or do something which might signal to others that you are good or virtuous, ask, "Would a purely selfish person have sufficient reason to make that same expression or do that same thing?" If the answer is yes, there's a good chance your motives aren't good.
For instance, if I say, "I advocate that high income be taxed more because I care about the poor," it makes other people who agree with me like me a bit more, but I don't actually lose any money. A sociopath who wanted to increase their own status in order to generate selfish benefits might say this.
In contrast, if I were to anonymously donate 40% of my income to the poor and tell no one, then I get no social benefits. So it's more likely to be a genuine act of beneficence rather than faking beneficence for self-interested reasons.
Of course, this is not a perfect test.
At any rate, in contrast, I prefer to vice signal. Vice signaling is a form of counter-signaling where you are so secure in your own virtue that you actively signal that you are worse than you in fact are. It's like when very rich people dress down in meetings.