Agree with infusions. I had no trouble getting them. Just tell you've tried oral as recommend and it hasn't raised your levels. They can't know what you've taken or not. You can also tell them that iron is painfully constipating you. Again, they just have to take your word.
In general, iron infusions are no big deal for them.
And for you, they'd be great. No more pills (or their expense) to separate from other pills, food, etc.
In my case, one infusion took me from just below range to way above it. It's just two hours sitting in a comfy recliner, reading a book. Can't beat it! I went nine months before I needed my next one.