Dude we all have mammary glands
Some very tiny that's impossible to feel
And some a little noticable
Gynomastia means that the gland is larger than normal youll feel a knot or squishy gland right beneath the nipple. Its also very sensitive if it's gynomastia

Squeeze your nipple and see if you feel something hard in there, also if your nipples are puffy.

Raise one arm up and stretch it out as high as you can go and touch your shoulder to your ear. Now look in the mirror. Is there a round lump you can see behind the nipple? Can you feel it behind the nipple if you can't see it? It will feel like a pebble or a knot. If you do, that's gland tissue that's grown. If you stick the tip of your index finger into the middle of your nipple and don't feel a lump or pebble you're good. If what's around the nipple isn't cone shaped (the breast tissue around the gland) then you're good.