I have postural orthostatic tachycardia syndrome. Bp 120/70 position changes it goes to 138/75. Prescribed midodrine should stop jumps?

Unclear. If by "jumps" you mean changes in bp, it may help. Midodrine is intended to maintain the BP and help prevent abrupt decreases in the BP with standing. Be certain you are drinking at least 60-80 oz of water every day.
NO. You're confusing pots and orthostatic hypotension with normal. The bps you list are normal. It is normal for systolic BP to fall slightly when you first stand, and then to rise above baseline a few seconds later. Diastolic BP tends to rise. Midodrine can cause severe supine hypertension - it will not prevent your BP from rising when you stand. It will add to it.