Thin womb lining help

Mr

So I went and had a scan today and all was well. I asked if he could see if I was pregnant as I am due on in a couple of days ( or hopefully not) and he said there was absolutely nothing there. He then said your lining looks a bit thin. That’s freaked me out and upon researchjng it makes sense as to why we haven’t been able to conceive. Has anyone got any tips to increase this or is it jut my age of 37 meaning lower east roger levels.