I think I would keep a food and symptoms diary for a couple of weeks and you can report back to your dietitian. Because you say it’s after eating makes me think it might be dumping and this generally happens more with sugary foods ( but not limited to just those)
Maybe think about a blood test too if you haven’t had one – are you taking your iron supplements ok.
liw blood pressure can cause dizziness sometimes too but wouldn’t be limited to after eating.
Def keep an eye on it and discuss in more detail at your Dietetic app’ s