Hi and welcome to the BW community! The average A time for LOs this age is 75-80 minutes, although the first A time of the day is generally a bit shorter and you need to shorten A times following a short nap.
Looking at your routine, it seems as though maybe the first A time could be stretched a little if she's sleeping at least 45 minutes. (45 minutes generally indicates UT, although in some cases it's OT) I think because it's over 45 minutes that she's sleeping, she's likely UT for that first cycle. Then I think because her next nap is interrupted with your DS's activities, she's OT for the rest of the day and short naps as a result. It's hard to find a happy medium, and when my DD 2 was this age, I struggled with finding the balance so that my DD1 could get what she needed too. I made sure that the rest of the naps during the day were in her crib, uninterrupted.
She sounds like she's an angel baby, though, and is coping well with the short naps. Pat/shh is a great tool for extending those short naps. It worked well for us, but I modified it and just held my hand on her chest and shh'd, since she has reflux and didn't like the patting. It sounds as if you're doing that but you could add the shh'ing and see if that helps.
As for your 2 yo, I know it's tough. I told my DD that she could stand quietly at the door or read books in her room quietly while I helped the baby to sleep. She always chose to stand at the door, but was generally pretty quiet... She puts her 'babies' to sleep by shhing them now, it's so cute! Anyways, if that doesn't work for you, perhaps you could work on your DDs naps with pat/shh while your DS is napping?
HTH! Let me know how you get on!