Okay...at this age, I think you should get firmer with resettling, as in, hang back and let her resettle herself if she wakes up early from a nap or at night. You're doing a great job at letting her send herself off to sleep initially, but let's see if by you not patting, she'll resettle herself. Just don't want the shh/pat to become a prop, iykwim. Going all the way back up to your original post, it could be that the shh/pat is a prop at night, but it could be OT/UT, too. Not sure exactly what you do at night, but DH and I have a rule that if DS wakes up during the night, we don't go into his room unless he's crying his "I need you!!" cry. That means that if he's cooing, babbling, fussing, or mantra crying, we leave him to it...even if it means it goes on for 10 minutes or an hour....I think that might help you rule out any prop issues with shh/pat at night. PU/PD is a measure of last resort, so let's see if by gradually reducing the shh/pat help you give her (assuming she really, really needs it) will help before we move on to PU/PD.
Also, related to props, do you think it might be time to wean the swaddle? It might be a rough few days while she gets used to the sensation of her hands being out, but I think it's worth considering.
Now, about those naps. Does/Has she always wake up at the 30 minute mark into her nap?
So far as her routine goes, is she showing sleepy signs at the 3.5h mark? Or do you feel that her sleep window is being missed? Since you're there with her everyday, I'd like to get a feel for what you think she's sleeping (is she grumpy or happy when she wakes? does she fight going to sleep?).
Sorry for the 20 questions, I'm just trying to hone in on what the underlying issue is.