good to see you are practising and have the 2 draw cracked 😉
Getting out of breath is a common thing,
try to focus on relaxing when you are breathing just like you breathing without the harmonica
Breathing out before you start the playing first helps to
another good practice is drawing a note as long as possibel start with one you do best first and builth it up try to focus on playing the note clean the whole time, then do it with all of the notes.
record yourself while doing this.
as always take it slow and focus on what you are practising after some time you will see improvement
relaxing at all times when playing is the key, the moment you feel tension you are of the track 😉
hope this helps you a bith
take a look at the step-by-step course Mitch has covered this for sure.