Is my baby not ready??

Baby is 5 months old, has always fed to sleep for naps and bedtime unfortunately. I didn’t realise how much of a tricky habit I was creating until it was too late. For the past week I’ve been bed sharing and feeding baby girl back to sleep throughout the night and she has all of a sudden decided she hates her cot, by pulling our mattress on the floor (I’m paranoid about baby girl falling off the bed) while my partner sleeps downstairs on the sofa. Obviously none of this is ideal and everyone gets a shitty sleep. I’ve been looking into different forms of sleep training and decided to go with a gentle one. My LO literally gets HYSTERICAL. What started out quite promising with sleepy fussing and babbling turned into her screaming her head off tears streaming down her face and her coughing she was crying so hard. This is with regular 60 second check ins and me actively soothing her. The ONLY thing that stops her is giving her my boob (exclusively breastfed). I don’t want to do a CIO, but all these sleep consultants and books I’ve bought constantly talk about letting her work out sleep herself and helping her learn self soothing. She does not self soothe, she works herself up more. I’ve tried this method of sleep training for short periods of time, and tonight I tried soothing her periodically for about 50 minutes. The longer time goes on the worse she gets. Is she just not ready for sleep training yet??