No EWCM during fertile window

Can someone tell me how to improve fertile cervical mucus? I rarely notice EWCM during fertile window and even if I do it is not much. Recently my RE did a cervical swab post-coital test and said I had no CM. They said without CM sperms can’t travel to the egg and the solution is to try IUI. I have been trying for baby #1 for more than 1.5 years.

I want to try to increase fertile CM naturally before trying anything else.

Can someone share what might have helped them?