4 year old not eating for 3 months

[Bogertophis]

She normally eats a large frozen rat every month. I've had her since she was a baby. Never had an issue with feeding. I had her humidity up higher cuz she had eye caps. She's normally (before I raised then recently) at 60 humidity. I mean the cool side of the tank is 75-78 and the high side is 85ish

You might bump up your temps a bit- cool side 78-80, & warm side 88-90. And you might be overfeeding too- that's why many snakes go on fasts. For the most part, adult male BPs should stay on small rats, & adult female BPs should stay on medium rats. I think she's trying to tell you something. And keep in mind that the speed of her digestion is dependent on the warmth available too. You're giving her more than she can handle on such a regular basis- when you back down to mediums, she's more likely to eat on schedule. Remember that our captive snakes just aren't very active either.