I'd probably let her sleep longer and see when she wakes naturally. If it got to 3hrs I'd wake as she needs a feed and by that time it is probably around 4hrs since the previous feed but I think it's unlikely she'd sleep as long as 3hrs.
As she is so young I do think it is expected that some naps go better than others. You can keep working towards a consistent routine but you are doing brilliantly. Getting 1.5 and 2hr naps is wonderful!
I doubt night sleep would be effected by a longer nap at this age (some can get day/night mixed up but this is not the case here). More likely she would have a long nap and then manage a longer A time - sounds like this could be on the cards if pick up disturbs her nap either because you have to wake her or can't get her home in time or she just wants to be awake to see her big sister