I hate to say it but unfortunately 45min naps are pretty common between 3-6 months - its a developmental thing - their little brains have worked on establishing a longer stretch of sleep at night in the first 3 months, & then they work on daytime sleep from 3-6months, after which longer naps will usually follow.
However, 45min naps can also be a sign of being undertired i.e. tired enough to fall asleep but not tired enough to sleep for longer than 1 sleep cycle.
Your routine says she is awake for 1.5hrs, does a 45min-1hr nap, then she is awake another 1.5hrs, and she does a 30min nap. Do you keep her awake for 1.5hrs regardless of how long she naps for?
To me that first nap may be undertired, and because she is then kept up for a full 1.5hrs before her next nap, she is overtired & so only sleeps 30mins, & this is why she is then tired all afternoon.
Could you try extending that awake period before the AM nap just by 5-10mins no more, and see whether that helps her sleep a little longer? It may work, but may not due to the developmental reasons above. If you like BW you could always try wake to sleep or HTTJ to try & get her past the 45min mark.
Another thing to note is that if she does do a short nap, I would put her down for her next nap a little earlier as she will be more tired. By doing this you might find she sleeps a little better, therefore avoiding overtiredness in the afternoon.
How is she sleeping at nights now - has that issue resolved itself?
freeangel - hope some of this helps you too. Personally I wouldn't limit the amount of daysleep for a baby of 8 weeks old. He needs his sleep in order to develop healthily, and being unsettled/waking at night is more likely to be down to overtiredness/health issues (silent reflux)/not knowing how to settle to sleep independently than not being tired enough. Is he on meds for the reflux? The GF routine provides excellent structure for his day although opinion from mums I know is that their babies needed a little more sleep than she recommends so they would put down when baby was tired but wake at the suggested timings to keep the routine on track. HTH.xx