Pull out/natural family planning method

I was on a few different hormonal birth control pills for 6 years, and they caused several different health problems in me (both progesterone and vitamin d deficiencies). I am OVER hormonal contraceptives because eventually I would like to have children, and I can’t handle the mood swings/health problems that SEVERAL different pills have resulted in. We don’t want to have kids yet, so my husband and I started using condoms. This is when we found out that I have a latex allergy. So I was curious if we had him pull out during my fertile window, how effective that would be as a birth control method? I bought a bbt thermometer and some opk’s and plan on using those readings to predict when he should pull out 🤔