Follicle scan after 3rd round of Clomid

Here is a little background on me: I have 1 child (almost 3 y/o) and have had 2 miscarriages since. All 3 pregnancies we conceived naturally. My husband and I have been TTC for 1 year 3 months. I have taken 3 cycles of Clomid 50 mg cycle days 4-8, last month received a trigger shot and nothing happened. Today I had a follicle scan (CD 12) and I have 1 follicle on my left ovary that is 16 mm. My doctor said she is confused as to why I don't have a ripe follicle and wants me to do another scan in 2 days (CD 14). She offered doing IUI but doesn't see why it would be necessary for me since my DH and I have conceived with no problems before. I don't know what to do and don't want to see another cycle go by, lost...any tips?