You don’t get to grade your own apology. The person you hurt does.

An apology is judged by whether it worked for the person receiving it, not by how good it felt to give. You can produce something sincere and well phrased and still find they are not ready, or that you missed the part that actually hurt. Their verdict is the only one with any standing.

After you apologise, ask whether there is anything you have missed, then be quiet long enough for a real answer. If they need time, let them have it without checking on the progress. Doing better next time is the part they can actually see.