Femara trigger & iui

I am on cd3 and just had u/s and blood work. I am starting femara today but my re said to only take 2.5mg. Last cycle he prescribed 5mg but I ended up not using it and just triggering early in my cycle. I am nervous that the 2.5mg isn't strong enough. I was taking 150mg of Clomid to ovulate. I was on that for 6 months after my m/c in February. I just don't want to waste another cycle. ? Anyone have success on a low dose of femara?