Hi!
First off, it might not be a bad idea to introduce a winddown routine at naptime. It doesn't have to be anything fancy, I used to swaddle my DD (which we eventually dropped), sing her a song, and put her in her crib. She does know now that her song means that it's just about naptime, so it sets the stage.
It does sound like your LO may need a longer A time right now. There's really not a ton you want to do at this age during A time, they get so easily overstimulated at this age, so things like looking out the window, walking around with you, looking at t mirror, looking at (or chewing on) a stuffed toy, laying on the floor or in a bouncy seat and just watching the world go by....
It's hard to tell when they're that small if they're fussing because they're overtired or not tired enough. You can try extending very gradually - just like Janelle mentioned over the course of a few days to see if it helps your naps out at all. And definitely wait to do anything until she's recovered from those 2 month shots. Poor sweetie, I always feel so bad for my DD when she has to get hers.
If it helps, I would check out the sample EASY routines for LOs of your age in the EASY forum. Might help to see what other moms did when their LOs were the same age as yours.