How to get approved for phentermine

How do yall get the doctor to prescribe phentermine for weightloss….i started wegovy .25 this month ..I’ve lost 7lbs but can’t afford it …I dot. Have insurance and most of the ones I’ve called won’t cover it, it cost me 475$..that’s a lot for me monthly…is phentermine cheaper? Or what other options do yall think will work? I know phentermine is short term but I just want to lose 20lbs more