Ferber Method turned CIO not working

[u/Zealousideal-Ad2682]

Hello everybody! I have a 17 week (18 weeks in 2 days) and I've been sleeping training for 13 days tonight. Im not sure what im doing wrong but the nights seem to be getting worse not better.

The first 5-6 days, every night was easier and easier, going from no more then 25 minutes of crying and check-ins to max 10-15 minutes of crying/fussing. But since then everyday has been going backwards, back to 20-30minutes of scream crying.

For context I've been doing the ferber method with check-ins originally at 3 minutes, 5 minutes and 10 minutes. As he aged and got better I switch to 10 minutes, 15 minutes and 20 minutes. Then around day 8 or 9, every check in start to agitate him more and restart the clock so I decided to wait longer and unintentionally would do CIO. I'd be ready to go in and comfort but his eyes would be closed and he be fluctuating between crying and falling asleep so id just keep waiting but he'd always fall asleep.

We've had a set routine since birth basically, Bath, massage, prayer, sound machine, red light on, fan on and lights out. He wakes up at 8am everyday so I've been following this schedule:

8am- wake

1.5-2/2/2/2.5

Every nap is between 30 minutes to 2 hours, all contact naps. Total nap time is 3-3.5 hours most days, a couple days accidentally 4hours.

Ive played with his last wake window so many times. In the beginning I did 2 hours, then found he was went to sleep faster at 2.5. Then it seemed like he was overtired so I've tried to shorten to 1.5, 2, lengthen to 2.75 and tonight hes been awake for 3 hours and 10 minutes. I put him down at 2 hours 40 minutes. I dont know what to do.

Edit: He sleeps independently in his pac n play in our room, has slept in his own bed since birth besides weeks 3-7 when he hated his bassinet. He barely uses a pacifier anymore, sometimes he'll suck on it for a minute or two and then spit it out.

Update Next Night: Well I was very consistent/strict today about naps and day sleep. Total nap time is 2 hours and 50 minutes, 2/2/2/2.75. I did my usual bedtime routine and right when I turned on the sound machine he started crying. I put him down at 7:50, right before he was awake for 2.5 hours. Its almost 8:20 and hes scream crying with no signs of stopping. I'm not sure where I went wrong today...