Hello Rachael and sorry for taking a while to respond.
Unfortunately, the InfoPath designer doesn't provide any features for adding and removing rows from repeating sections. If you want to do so, your two options are to (1) write your own custom code, or (2) use a framework like qRules, which is based off of code, but abstracts it away into an easy to use system. We tend to advise against using code because it makes the form a lot harder to maintain, especially if you aren't an experienced coder, so I highly recommend giving qRules a spin.