How do I know if my swelling is normal, or preeclampsia?

nofrogs

I have developed pitting edema in my ankles, and my feet are really big and swollen. I can't even wear my husband's enormous socks.  My feet feel really sore, but I did walk around IKEA today. I called my Midwife practice and the MW on call is in a birth right now, and said to call back later. I am not experiencing headaches or nausea, or any other symptoms.  

I am really anxious, because a coworker of mine just delivered a 29 week preemie, due to PE. I put my feet up for an hour or so, and it didn't really help. Any tips? Maybe I am overreacting, because I am a first time mom, and I am thinking about this coworker of mine.