The purpose of the opening is to get yourself to a playable middlegame - so whatever moves make you feel comfortable (and hopefully, don't violate the general opening principles) will be fine. It's hard to put a numeric value on what you're "losing" by not playing book lines and instead going on general principles alone. In general it'll be very little, but at some points you will fall into known traps that leave you much worse.
But for a beginner, just playing the opening on principles is fine. Focus on more important things - like you said, tactics (namely not dropping pieces and making counting errors to start with).
Edit: Looking at your games, you're not a beginner in the sense I was thinking, so kindly disregard my comments, for the most part.