Ferber method - sleep training for my 6.5 month baby girl

My daughter is 6.5 months old & I started 2 nights ago ( tonight will be day 30 for night time sleep) Ferber method. The first night took around 20 minutes, and she got up once at 5am that took about 1 hour & 15 min hours to get her back to sleep. I didn’t nurse her I tried my best to just hold her but of course I put her down in the crib she got up. She always slept through the night and started to wake up at 4 or 5 am most nights about a month ago and last week I would nurse after giving up after 15 minutes. Last night another 20 minutes to go back to bed and she slept until 6:10 am. I even tried with her nap yesterday took 8 min. Today it took me around 20 minutes to put her for a nap. she only slept for 30 minutes she woke her self up by flipping on her tummy, I saw she was tired still so I started again with the timed interval I tired for almost 30 min nothing worked so I fed her. I read in a sleep program that if they can’t nap in half an hour then to basically try again later. Should I just have taken the half an hour and not attempted again. I thought Day 2 of napping would be better. I notice she keeps flipping on her tummy & stays there and cries. Any tips advice ? Thanks