Is it normal to sound airy? Usually in the evening, I feel like my sound is getting airy. Still wondering if is normal or I’m just bad :D

No, it's not normal to sound airy. Airy is usually a sign your embouchure is tired.

You can build the endurance by breaking up practice and allowing 10-15 minutes between playing sessions to allow the lips to recover a bit.

You are better off playing 3 15 minute sessions with breaks than going for 45 minutes straight.