Starting letrozole tomorrow, am nervous 😔

Hi, I am so grateful to find this group. Taking letrozole (this is the same thing as fermara right?) for the first time tomorrow for the first five days and am really nervous and scared. I have never taken fertility meds before. I do not have any diagnosed fertility issue (yet), my scans have been all clear and blood work, but trying to conceive my 3rd (2nd on earth) after a miscarriage with my first, and my 2nd is now 2 yes old, but havent been able to conceive the past 8 months for some reason and I am about to turn 35 so the doctor prescribed this and an IUI this round. I desperately want to have our next baby and fear im struggling with secondary infertility.

I had an unmedicated IUI last round, no success.

I take zero meds and have heard fertility meds can come with bad aide effects and letrozole is also given to breast cancer patients? Are there any chances of this harming my baby if i conceive or my body? Any advice or experiences you can give please share. Thank you so much.