This is VERY normal. Some things that were suggested to me by others when I went through this:
1) have a small basket (or baskets!) of "special toys", things that ONLY come out during breastfeeding time. It gets put away immediately when baby/mommy are done, so that the novelty stays for a while.
2) get new books (send somebody to the library -- cheaper!!) and have story time while the baby is nursing. If you feel like you don't have enough hands to do this, get those board books and start teaching your older child to handle books gently.
3) have a selection of videos to watch during nursing. These don't all have to be stories; if you can find any that have little kids dancing or exercising, etc., it might help her use up some extra energy!
4) sing with her, recite poetry, work on ABC's and counting, teach her "I Spy With My Little Eye" -- activities to keep her mind busy while you nurse!!
I'm sure there are more -- I just can't think of them right now!
I think that the "learning curve" with baby #2 is sometimes steeper than with #1. It's a whole re-arrangement of family priorities, "positions", etc. It's very easy to worry about not giving the baby your undivided attention, like you did with #1; however, second babies seem to somehow figure out quickly that they need to "fit in", and it's easier for them to handle that, than it is for baby #1 to feel like they've somehow been demoted or are less important. Activities going on during nursing will be the "norm" for this baby; you're not giving her less!! She's part of a "team"!! Besides, I suspect that there are plenty of times (especially during the night) when she will get one-on-one time with just mom. When big sister is around, try to keep her feeling important, needed, and loved. It will all work out -- please make sure you're taking care of YOURSELF, too.