Hi and welcome to our community!
First of all: you're not alone with this. Unfortunately, this is a problem many IBS sufferers experience. Here's an article from one of our contributors about her experience with the paleo diet, for example: https://irritablebowelsyndrome.net/living/paleo-diet
For me, every time I tried to eat healthy in the past it just caused me SO many digestive symptoms and I'm pretty sure that being sick all day wasn't in fact 'healthy' for me.
That being said, what works for me is balancing vegetables with carbs. So if I'm trying to eat a healthy meal, I'll add white rice to it so it doesn't upset my IBS too much. Eating smaller quantities of veggies also helps me.
As for losing weight, some form of intermittent fasting works really well for me AND it also helps my IBS. I actually stopped eating dinner at one point because my IBS would flare really bad at night, and I lost quite a bit of weight without even trying. We're all different though, so it's important to find something that works well for you.
As for probiotics, I would definitely suggest discussing them with a doctor or pharmacist first, as there are so many different kinds. I've tried several different ones and some made my symptoms worse, while others work well for me. Here's an article about probiotics and IBS that might interest you: https://irritablebowelsyndrome.net/treatment/probiotics.
I hope that other community members will soon share their recommendations with you! Wishing you all the best, Karina (team member)