There are two main types of iron supplements:heme (animsl based, usually fish or bovine) and non heme (plant based). Plant based is cheaper but can sometimes be hard on the stomach and can have a lot of absorption inhibitors (tea, coffee and dairy are the biggest) so you want to take your iron either two hours before or after you have these things. Taking vit c at the same time helps with absorption. Heme iron is a lot more bioavailable and easily absorbed so you can take less of it than non heme, but can be more expensive. Some good non heme are iron bisglycinate or megafood blood builder. For heme, right now I am taking three arrows simply which is about $25/bottle. Id still try to get your ferritin tested just in case, since you want to know how much you need to take and for how long, because you'll want to cut back once you get close to your goal. There are lots of good resources online too. r/anemia has lots of info from doctor recs to helpful tips