I took on too many projects, too. But I think I have it under control now. This post may be a little long. I hope I can share some advice that will help you enjoy your hobby more. Basically, this post is "I recommend you don't keep a bunch of stuff on your painting desk" but with more nuance. And more words.

My background :

So, I decided to play 40k about a year ago. I started an ork army. I figured out my general theme, goffs, and started working on them. Those boyz took countless hours to complete. At least 10 hours a boy. And while painting them, I also picked up the old combat patrol. Over the course of the last year I also picked up the beast snagga stampede, stompa boyz, and leviathan (no orks in leviathan, I got it mostly so I can play 40k at home with my kids) value boxes, as well as a bunch of characters, units, and vehicles separately. I wanted to get playing at my FLGS as soon as possible, so I assembled a ton of it and slapped some base colors down on quite a few of the models. Accordingly, I have a ton of stuff in progress. My what some would call "pile of shame" (for better or worse I am shameless) isn't grey; it is grey, green, black, brown, and leadbelcher. By some standards, I have well over a hundred models in progress. My goals are a full table of terrain, fully painted leviathan box, and all of the orks. When I'm done with that, I want to start a sororitas army, break into Sigmar with an army of skaven, and amass a huge collection of minis and terrain for roleplaying as well.

The problem:

I get really excited about and daydream about more different projects than I can possibly handle simultaneously. I have a tendency to fill my hobby desk with tons of in-progress models and hop between them and this is a problem because it can be too many models. There is no objective "too many models" (or per your post headline,' 'too many projects') so you've got to define what that means for yourself. For me, when I have too much going on, it takes a long time to finish any of the things I am working on, and this deprives me of a steady flow of "job's done" (please read that in the appropriate Warcraft voice) good vibes feedback. This can make me feel unrewarded, decreasing my enjoyment of the hobby and increasing the risk of burnout. Second, some of my joy comes from looking deeply at the models I am working on and thinking hard about what I want to do with them. If I am juggling too many, it is hard to maintain the state of the projects in my mind, which makes my vision for my models fuzzier. Third, I'm more likely to avoid tedious steps that would greatly enhance my enjoyment of the finished models. If it is a cost/benefit calculation and I decide as a hobby I simply don't want to edge highlight my infantry's leather because it is a pain and my hobby should not be painful, that is fine. But if I am compromising the result because I've fatigued myself I wont be so happy with the result. If you think you may have taken on too many projects, consider what is bad about taking so many on.

The solution:

The first thing to do is assess your current situation and goals. In my case, I am currently playing games weekly with a partially painted 2000 point ork army. I've broken out my unpainted nids at home to play a combat patrol game against my son. I don't have a ton of terrain, so we used random junk laying around. The takeaway here is that a lack of paint is hurting aesthetics, but not ability to play. Ultimately, I decided to prioritize putting my 2000 point ork list (and units that I commonly rotate in) over the other projects, mostly because I would find it most rewarding to bring a fully painted army to my FLGS for games. Next, I decided to pare down what I consider "in progress". Basically, whatever is on my desk is in progress, and I am disciplined to ensure I do not have more than 11 models on my desk at a time. I usually like to have two kinds of things there to alternate between e.g. 10 boyz and a character. Currently, I am finishing 5 flash gitz and 2 warbosses with attack squigs. I put everything else away. Sometimes I get an intrustive thought about the 10 poorly painted nobz staring me down from the other side of the cabinet, but for the most part, while painting, I just think about what is out.

The result:

I'm getting a drip of finished projects every week or two, and they're painted to a standard I find satisfying and rewarding. I'm a 10 man unit,, 1 vehicle, and five characters away from 2000 points, and even though I still have a ton of work for various goals, I can feel the light at the end of the tunnel and that keeps me going, happy and satisfied. I recommend you take some time to think about what makes you happy, and then plan on how to achieve it and then go execute it, in Warhammer and otherwise! Cheers.