Hi. I have some experience of this. My Hb was 8 and my ferritin was 2! I felt dreadful! Short of breath, constant UTI's and knackered. This was a year before TTC. It dropped again when I was pregnant, but never got that low again. Once corrected, I took a multi vitamin with iron as maintenance (check multivitamins don't have Vit A though when TTC/pregnant).
I'm surprised the 'highly recommended clinic' didn't run full blood tests as part of the regular MOT and pick up the deficiency then! When I had fertility testing, along with STI screening, checking bloods for anaemia, thyroid, sugar, U&E's, FBC etc was the norm.
I'd suggest buying the book 'It starts with an egg'. You can get a 2nd hand copy from ebay. Just some handy tips of day to day things you can change to hopefully increase your chances.
Along with taking the iron supplements, dietary changes can be almost as affective. Take your meds with Vit C rich food or drink- glass of orange juice, peppers etc. Reduce your tannin intake, which depletes iron absorption, so reduce or cut down tea/coffee/red wine etc and certainly don't have them at the same time as your iron meds. Your body takes 3mths to replicate new blood cells, so it won't be corrected after a week or 2.
Unfortunately, I don't have have a success story to share. We TTC 12yrs, had rounds of IVF and lost 3. Nothing to do with anaemia though. There was never any cause for sub-fertility ever found. Just one of those things. Wishing you all the best of your journey.