Hi, i had the same problem as you last year. I am a sophomore as well and i started in spring of Freshman year but i couldn't even clear six. I would never run tall and always stride out in the end. Many factors that caused this was an incorrect pole hold/drop. Make sure your shoulders are relaxed and you drop the pole as ayou run down the runway. Also don't start with the pole tip too low because it will be harder to hold. Moreover, running tall was very difficult for me (still is sometimes) but focus on making your first few steps the biggest ones. Don't overstride, but make them your biggest and smaller in the end. Try running wiith your knees higher. A few drills to help with this are high knees 20-20 drill (20 steps in 20 meters), I don't know the technique your coach teaches so i do not want to tell you how you should take-off, but what i learn is to jump up off the left foot, make-space with left arm, swing and pull. Once you get the pull down, you turn naturally, and it helps you go higher. Chin-ups, pull-ups, box jumps and bubkas should help with the jump, swing and pull.
By the way, i couldn't clear 7' my freshman year when everyone else on the team was clearing it now my PR is 8'6 and i am right up there with all the other girls . So learning all this was really helpful to me.