Good luck to you!
I know how that goes, being too busy to market. One easy thing you could do that won’t take much time is to email all of your old clients individually (not BCC, copy/paste into a new email and change the name/company name) and check in to see if they need anything now or know anyone who does (get those referrals!) and maybe even offer some sort of new year deal.
Also, send a newsletter out to your mailing list (if you have one) wishing them a happy holidays and maybe either offering a special for work starting in January or just a new blog with valuable content for readers — remind them you’re there!
I hope this helps and it sounds like you’re already doing great!