Follicles are slowly growing. Help!

Ashlee

So last month I took 5mg of femara and my follicle was already 20mm at cd 11. I ended up not getting pregnant. This month I took 7.5mg and on cd 12 I had two follicles at 10mm and then at cd 15 they were only at 11mm and 13mm. What would cause them not to grow? I’m super confused. My doctor didn’t really give me any answers.