Anxiety

OK...lots to unpack here but don't we all. 

I also sleep like crap the week before a race - I'm guessing there's some degree of taper madness and pre-race anxiety especially the night before.  How I've tried to accommodate this is really double-down on everything that helps with sleep:  food choices, pre-bedtime routine, mindfulness/meditation, even taking a Benadryl, the works.  Helps a little I guess.  I'm with you in that being exhausted takes the fun out of it, even if it doesn't always crush your performance.

When you saw your sports psychologist, did he/she give you a plan to follow going forward even without their assistance?  Having someone to talk through it helps but if that's what got you through it, and you stopped using it, you're back to square one.  I'd start planning out your taper week including those types of things. Talking to someone about it helps even if they're not a professional. 

Also how you taper (the types of workouts) matter.  I've seen athletes over-taper and basically stop training for a week before a race and that will kill your performance plus make you go crazy.  Taper is about reducing volume, not intensity, so make sure you get good workouts in that week (and those endorphins from shorter workouts). 

Also you mentioned that you don't care about how you place other than doing well yourself, then later you say you see people improving faster than you are, which is comparing yourself to others.    That's OK, we all do it.  I see a lot of the same triathletes around here at races and I can tell they take it way more seriously than I do and it shows.  I took a race very seriously earlier this month trying to qualify for Age Group Nationals...I had a couple of bad things not go my way early and I spiraled and laid a total egg in the race.  It happens.  Next month I'm doing a local sprint where I'm just going to say "F@#$ it!!" I'm going to have fun today and enjoy it (which I've done in the past and I often perform better). 

Another thing to suggest would be to really nail down your race prep.  Get all of your crap together a couple of days early.  Practice a transition in your living room.  Have everything raring to go for race morning well in advance so the only thing you have to worry about is waking up and getting your body physically ready to go.  Before the race, I always try to practice a few minutes of mindfulness, allowing me to recognize the work I put in, all the positive energy around me, the newbies who are way more stressed out than I am, and remember that what we do is really cool and not everyone can do it.  Last race I missed that part of my pre-race routine and I felt it. 

One more...try a couple of "C" races in your schedule where you literally are using them as training/fun events.  Heck don't even wear a watch.

We've all been there, and we're all an experiment of one trying to figure this out.