Thank you for writing.
You said you don't eat meat regularly but there is a big difference between that and being vegan.
If supplements are not working for you and you don't want to eat meat, you can find iron (from https://www.eatright.org/health/wellness/preventing-illness/iron-deficiency) from :
Beans and lentils
Dark green leafy vegetables such as spinach
Fortified breakfast cereals
Whole-grain and enriched breads
I'm not sure if being in your 40s is a cause. Iron is best absorbed with vitamins A and C.
A nutritionist can help you further.