u/Medical-Meet147

My 3.5 month old won’t nap beyond 20 minutes. Every time. In my arms, the crib, the pram. She does sleep longer in the sling but she is so heavy now so only her dad can walk her around for an hour.
I wouldn’t mind if she woke up happy or somewhat refreshed. But she gets more miserable throughout the day and I know it is because she is tired.
I try blackout, white noise, same sleep environment at night.
At night she sleeps like a dream!! Only one wake up. So whyyyyy won’t she sleep during the day? One day she napped for 40 minutes then for 1h20. I was so happy! But she hasn’t done it since! I do t think I did anything different
Any advice welcome!!