As a fellow introvert... don't fee like your kids have to be in a ton of outside activities. For us, ours did ONE. And mostly it was ONE that they all could do together in these younger years.
LIke, story time at the library. All 3 of mine could go up until the boys aged out and by then, my daughter was beyond the crafts and stories anyway because she taught herself to read at a young age.
Dd did horseback riding and the boys did karate. That was IT for a while. NO baseball, soccer, boy scouts, 4 -H... nothing.
They all three took tennis lessons one school year only because they all three took them in the same class! One trip for me driving them there... not 3 lessons at different times.
Same for swimming lessons.. all 3 going to same lesson. Not individual classes.
They all 3 did do Awana's at church, and over the summer, the VBS at church.
This way they got their socializing and I didn't have to do a ton of driving them around to each individual activity.
We did one field trip a month with the home school group IF it was something we were interested in. We did do the once a week play dates at the park (which they enjoyed more than the field trips, anyway!)
Even with our limited outings, there were weeks when I felt like we were going every single day!
So some things had to wait until they were older... like weekly bowling with the home school group... that waited until my children were teenaged.
Co-op classes with the home school group.. again didn't happen until they were high school aged.
My point is: Don't feel like you have to put them in every single activity when they are young.. there is plenty of time for them to be involved as they grow older and their interests change.
There were years where we did nothing but church activities, just because they were young and mom was tired!