IUI with injectables

I just did my first

IUI

taking letrozole pills 2.5 and then a trigger shot. I had 3 follicles all over 20. My nurse called today and wanted to plan ahead in case it didn’t work (won’t know til Feb 3rd) and she said my insurance wants me to do one round of

IUI

with injectables before we can do

IVF

—- I’m fine my husband has morphology issues so

IVF

icsi will help his issue...I’m now nervous I’ll overstimulate- are there low doses of injectables that are the same as the pills? Are the side effects worse?