I want to go CRO/STO. I’m 4 reps short for sit ups and pushups and my swimming needs to improve. If I barely pass the officer PAST would I have a realistic chance of getting selected for OCS?

I wouldn’t recommend going to selection with numbers that are barely passing, because there will be others there that are absolute machines. Go in as prepared as possible. You are expected to lead, and to exemplify the standards so you can help the team. It is not extremely difficult if you go enlisted first and then go officer, but I would recommend going for the job you want now whether it be CRO or PJ.