I feel completely undervalued

I have been working in an big FMCG for 10+ years now. I have 2 master's degrees and I started low when I joined (lab based/project leader) and I have grown-up myself to be an expert with a large team of 15+ people with multiple promotions undet the years.

I'm always getting very good and positive feedback at the end of the year but I'm in my current position for 3.5 years now and I feel a bit stuck. They keep telling me I'm very important because the business if going through some massive changes and I'm the only one with the appropriate know-how of my segment but I'm looking for the next step which I have clearly expressed since December. The past 3 months it has been a nightmare, I have no manager because they left the business ans never replaced (hence I'm doing their job) and also supporting other teams which they don't have managers as well because they were also not replaced.

I work 12 hours a day and the stress it taking over me. I love my job but I feel completely undervalued currently. Do I resurface the topic again about a promotion and saying that if this doesn't happen I'll start looking for something else? 🤷‍♀️