Sports Bra for PE?

F

Hi, I'm a freshman and just started school. You could consider me busty at a 38D almost 38E, I NEED my high impact sports bra. I have PE 6th period and was wondering what I could do to help my situation. I need to wear it but don't have enough time to change bras, as I am also a bit modest or shy. My plan was to change into my sports bra during lunch(we run on a block schedule, tomorrow I have homeroom and classes 2 break 4 lunch 6) Should I stick to this plan? What are your tips?