No, sophiasunshine, no, no, stop! The kind of "making sure" you are encouraging Anonymous to do is only going to make her OCD worse and lead to her ruminating even more over whether she accidentally lied. OCD is called "the doubting disease" for a reason -- people with it (like me) have a really difficult time tolerating uncertainty, but the sad fact of the matter is that the ONLY way to get better is to accept the thoughts you're having and accept the uncertainty.
That sounds really bad at first -- the idea that you may never be certain about whether you lied or not, or if you deserved your place at university -- but it's what you've got to do. Uncertainty is the way to go for things like this.
Next time you have the intrusive thought of "what if I lied and they base their decision on that?", just ACCEPT IT. Say to yourself, "yep. That may be true." And then try to move on. I know this is like walking uphill when the ground is sliding out from under you -- believe me, I know -- but you've got to do it. It's hard at first. It gets easier. Every time you have an intrusive thought, nod to yourself and agree with it. And then carry on as though you never had the thought in the first place.
Doing this will increase your anxiety levels for a while; there's no way around it. But that's what you want to be doing. You said you've dealt with OCD before -- then this should be familiar to you. Your obsession is whether you lied, and the compulsion I can see based on your post is ruminating about it and analyzing it and trying to "figure it out", which is detrimental to recovery. Accepting your thoughts and allowing that anxiety to flow -- without letting yourself do any compulsions -- is the only way to get better, because you learn to tolerate more and more anxiety. And eventually, the obsession seems silly, and you can move on with your life.
You might stumble a little and have some setbacks. That's normal and okay. But you CAN and WILL make progress with this. It's just a matter of facing your fears, accepting uncertainty, and not letting yourself take the easy way out by compulsing.
Hope you feel better and good luck!