Left eye dominant yet right handed

I was supposed to be left handed but I naturally chose to be right handed when I was younger. due to this, my dominant eye is my left. when playing sport I find it very difficult with hand eye coordination ( since I use my right hand for sport and left eye for aiming etc. ) I have my proper GCSE sports exam next Tuesday and I feel so rubbish! I tried playing javelin yesterday for a moderation and I couldn’t do the run up and throw the javelin properly because my brain just got confused. I need tips !! I don’t want to fail ☹️ thank you in advance