Hi Shannon,
Have you tried extending your naps by using Pat / Shhh. You could also try going into her room just before the 30 minute mark, and put your hand on her and when she jerks, you can shhh her then to help her transition into a deeper sleep.
After the 5pm feed, I would just let her have a cat nap of around 45 minutes then wake her, you can do your bath as your activity, then feed again after the bath, then start your winddown routine for bed. If she wakes at 8 - aim for a 8 bedtime, if she wakes at 7, aim for a 7 bed time. Although ideally you want to try and get her in bed by 7:30ish latest.
With doing the cluster feeds you may find that she will be able to go longer and won't wake up before the dreamfeed.
I am not sure what to suggest about the medication - perhaps just taking time for her system to get used to it.
It can take up to a week for the dreamfeed to be effective and start working, so it may be worth persevering with it.
HTH, Let us know if you have any other questions.
Paula x