What is her EASY routine? What time does she eat and sleep? Maybe post the last day or so If she has slept 45mins then I wouldn't try to resettle for more than 45mins unless she looks very close to sleeping again as she is bound to be hungry by then.
Was she on a routine previously and your stretching it to 4hrs or is this the first time she has been on any type of regular routine?
It could be that she needs to be awake a little longer before her nap and the 45min naps are UT or it could be that she just needs help transitioning to the second sleep cycle. 45 min naps are very common between 4-6mo and can be developmental. We'll be able to offer more advice when we've seen your routine. Wake to sleep might be something to consider if it isn't UT that is the issue.
Personally I would not give the paci back now it has been 5 days without it. I'd keep going as she shouldn't have such a need to suck now as when younger so it will only become a prop I would think.
Ah, posted with Haribo
seems we have a lot of the same ideas.