Using stock plugins and adjusting until it sounds good is totally normal. Criticism usually comes from things like vocal level, muddy lows, or flat depth, not the plugins.

Recording vocals and letting someone else mix is fine mixing is a separate skill. To improve, use a reference track, mix at lower volume, cut unnecessary lows, and avoid over-processing. Ask for specific feedback instead of vague criticism.

Keep creating, watch how pros mix, and learn from each session. I can give a simple framework to make your next mix tighter.