So, I'm coming from a carnivore standpoint here, which I realize isn't your thing. But, it's possible that your issue is with the veggies you're eating. 15 servings is a whole lotta veggies!

When I was starting low-carb Atkins in the late 1990s, I ate more veggies than ever in my entire life. And I became terribly constipated. I was downing fiber laxatives daily, and it only got worse and worse.

Whenever I cut way back on my veggies through the years, the constipation disappeared. Now that I'm carnivore, I have no issues. I poop 2 or 3 times a week, and am fine with that.

You can get all the nutrients you need from animal-sourced foods, even Vitamin C. It's something like a pound of meat per day provides all the Vitamin C you need. I've been doing this for 4 months (still a newbie), but others have done it for 10 years, 20 years, and beyond, and do not suffer from scurvy.

There's even evidence (you'd have to read up on Paul Saladino, Shawn Baker, Amber O'Hearn, and many others) that plant-based nutrients are not bio-available to humans and so we don't really get anything from them. Whether that's true or not, I'll leave to others who are smarter than me.

This is just a thought. You might just be getting too much fiber in your meals. As a test, you can cut it in half. Even at 7 servings per day, that's way more than most people eat.