Yeah ... you're not alone in this. I'm having a neuropsych exam in a few weeks to figure where/ how bad my deficits are.
But .... can I suggest a little different approach? I'm sure sometimes people notice something is not quite right with me ... because something is NOT quite right with me. My wife and I went to a small zoo today that's not too far away. So I'm doing my usual walk for a while then sit in the shade for a while. So ... I was sitting on this rock in the shade and one of the workers asked my to use a bench (they were in the sun). I told him I just wanted the shade and would find a bench in the shade. I walked off and I'm sure he noticed that everything was not "quite right".
So, anyways, it turns out that after i wandered off he asked my wife if I needed anything or if he could help in anyway. Not everyone wants to judge us. Some want to understand and help.
Just an observation, but trying to hide a condition like this is consuming a lot of your energy. When you meet people people at the reunion, you can just tell them you're having a problem. Laugh (it puts people at ease) and just tell them to please forgive any "senior moments" you may have and that's it's a problem left over from Lyme Disease. Don't have to make a big deal of it - but you won't have to waste any more energy trying to hide it.
RD's advice is very good. Can you take someone with you? I'd hate for you not to go to your 30'th. And anyways, this is the over 45 crowd and a lot of people will have health issues of one kind or another. Aches and pains and lotions and potions are always good conversation starters.