I know what you're thinking. What's BBT and why am I asking if you're down with it? What if I told you that you are capable of achieving or avoiding a baby bump (with 99.6% efficacy) without pills, patches, shots, or inserting thingamabobs into your uterus?
Not shitting you, this is real.
BBT, or Basal Body Temperature, is your temperature measured first thing when you wake up. This, combined with observing the changes in your cervical fluid throughout your cycle will reveal when you have ovulated, so you know when it's go time or no time in the conception department.
I know it sounds like snake oil, but rest assured, it's not. Fertility Awareness Method (FAM) is its name and understanding your body is its game. Not to be confused with any unreliable hippy dippy methods of unplanned pregnancies past, this right here, is the real deal, Holyfield, and its backed by scientific principles that track our bodies two primary signs of fertility. Kindara has created a beautiful, user-friendly app for keeping track of your daily data. It also lets you add in custom fields, like when you workout, when you go boozing, or when you travel (all of which, have the potential to affect your cycle). They also came out with a fancy thermometer that syncs with its app, but you can find an inexpensive digital thermometer on Amazon or your local drug store for under $10. If you've been grossed out by what goes on down under, you need to learn to embrace what you see in your panties, ladies. Amy Schumer knows what's up.
For a deeper understanding of FAM, I highly recommend you pick up a copy of Taking Charge of Your Fertility, a book that has a permanent spot in my home library. It's the definitive bible of all things fertility that you'll reference time and time again. It was incredibly helpful when I first started using this method. I also found this Ted Talk with statistician Talithia Williams a reinforcement of the significance of getting in the driver's seat of your own health.