Femara dosage decrease

I got pregnant with my daughter on 5mg Femara cycle 3-7. Now my daughter is 13 months old. We’re planning for baby #2 and have been trying to get pregnant naturally but I doubt it because I have pcos. I just got a new obgyn doctor and I told him about my infertility problem. He then prescribed me with 2.5mg cycle 5-9. I called to his office and his nurse was saying that the dr wanted to start the lower dosage first. Should I be worried that the dosage is too low to get me ovulate? Did anyone have experience something like this before? I have never do 2.5mg so I’m not sure that I’ll be ovulated.