Hi there and congrats on your new lo
I was there too, trying to juggle naps and loud toddlers and justifying time spent with each and the guilt over not getting things done 'right' with either of them.
I turned on my tv. I know that sounds horrible, but it's a great distraction for them and can keep some of them occupied for 1/2 hour stints. I use it now, as I'm currently working through a sleep issue with my youngest and it prevents my twins from killing each other.
When E is down, we do cuddle time, crafts, stories etc. Now that it's warm out we go outside a lot to let them run around. When the twins used to nap, I would sit in their room with E and try to arrange to be feeding her while they went down so she stayed quiet.
Now that I'm working on a sleep issue with E, they go across the hall in their room with a show on the tv and the stairs gated so they can't go down and I know where they're at. This does mean that we moved a tv into their room
, however it is ONLY used when I'm alone and trying to get her to sleep without disruption.
We had a short time where I could get the girls down first, I put on white noise so they didn't get disturbed by me getting E down for her nap. I was able to do this a few times per week but resorted to the tv other times.
Lastly, forgive yourself. Your lo is 9 weeks old, so at this point you're surviving more than anything. Have your toddler cuddle up with you while feeding the baby and if they want, small things like handing a diaper to you can go a long way. If you need to pop the baby in a sling to get more time in with your toddler, then do it.