Hello ladies,
I need some advice and tips on sleep training (both bedtime and naps).

About a month ago I started sleep training my lo (19 weeks old) via CIO for bedtime. We established the following routine at bedtime (any time between 8 - 9 depending on her last nap):
Bath, feed, read, feed a little more, sing, put in crib.
We often extend the feeding or singing portion depending on the lo. we wait for her sleep cues before saying good night and putting her down in her crib.

The first night she cried 45 minutes, 33 minutes on night two, 33 minutes night three, 5 minutes night 4, then 30 minutes (give or take) since night 5 for the past three weeks.

Sometimes the crying is more like loud whining, sometimes its legit crying. Once she's asleep, she can stay asleep until 7am, some days she'll wake up around 4am for a feed (at which point i bring her into my bed to nurse/co-sleep until the morning).

I spoke to our pediatrician about her 30 minutes of crying and he asked:
1) is she happy to see you when you get her in the morning? Yes.
2) does she sleep through the night? Yes.
He believes, given our answers, that 30 minutes of her crying might be worth it since she sleeps through the night once she's done. He also suggested that i stop bringing her into bed with me when she wakes for her night feed. (instead i should feed her and put her back into her crib and let her cio).

I read Mrs. Bee's sleep training Charlie post and decided to nap train my lo. Maybe she's getting confused that she's allowed to nurse to sleep for her naps but not for bed.

Here's what our nap training looked like today, her first day:
7am Feed/Play
8:30am Nap - 10 mins crying
11am Wake, Feed, Play
12:26pm Nap - 13 mins crying
1:10pm Wake (i let her cry until 1:20 hoping she'd put herself back to sleep)
1:20pm Wake, feed, cuddle
2:33pm Nap - 27 mins crying
3:30pm wake (extremely upset)
4:00pm Nap - let her nurse to sleep in my bed.
7pm - Wake (finally in a good mood from the 3 hour nap)
8:30pm - put in crib after bedtime routine. it's been 30 mins and she's still crying.

Does anyone have any suggestions, tips, advice or comments?? i'm at my wits end because none of my books or research online really addresses this kind of situation where the baby's CIO doesn't get progressively better. Should I continue CIO at all? Should i try nap training again tomorrow??