You might want to acquire a copy of David Vinings' "Range Songs" book. It has exercises going from high concert F to super-F, five exercises for each, plus low exercises going from low F to pedal Bb. If you're not taking lessons or getting some coaching in another way, you might want to start doing that, as well.
David Bjornstad
1923 Conn New Wonder 86I, Bach 6 1/2 AL
2018 Wessex EP100 Dolce, Denis Wick 4ABL
2013 Jinbao JBEP-1111L, Denis Wick 4AM
2015 Jinbao JBBR-1240, Denis Wick clone mouthpiece of unknown designation
Cullman (AL) Community Band (Euph Section Leader)
Brass Band of Huntsville (2nd Bari)