Afraid i haven’t planned enough

Do you have a hair and makeup artist? If you're planning to get one, I would book one soon!

You're totally where you should be, and yes it's a good idea to get hair and makeup booked and look for your FH/groomsmen attire sooner rather than later, but those were both pretty quick for us (~6 weeks from order to final fitting for DH's Indochino suit, some groomsmen ordered their suit rentals from Generation Tux as little as 30 days out and it was fine).

The things that really crept up on me and stressed me out in the last month or two were: 1) Practicing first dances!! (and breaking in my shoes, I never did much of that but thankfully was fine day-of). 2) Ordering the little stuff (like you mentioned, guest book and ceremony items) and waiting for it to arrive (COVID delays are no joke so I'd recommend ordering no less than 2-3 months out in case you have to deal with international shipping). And 3) printing for stuff I designed myself or used Etsy templates for e.g. menus, programs, table numbers, place cards, memorial photo display, etc. The more you can nail down those details ahead of time, the better - then when the big day gets closer, you're mostly just dealing with late RSVP's and confirming final guest count with your venue. And more importantly, taking care of yourself and FH! I was doing too much final-detail stuff the last month when I should've been turning my bathroom into a home spa and sipping a glass of wine, LOL.

Also - if the feeling of "I must be forgetting something" is stressing you out, I highly recommend making a comprehensive list / spreadsheet of all the stuff you need to have and things you need to do so you can just add to it as you think of things. Then check it weekly for now, daily in the last month or two to see if there's anything you're forgetting. I didn't create my spreadsheet until about a month out, and I wish I'd done it sooner bc once I did it really helped quiet that little "what am I forgetting" voice. :-)