Pads v. period undies?

Have any of you tried period undies? I have a fairly heavy flow the first 3 days of my period, so I'm nervous to try them and don't even know where to begin. I can't use tampons as they are super uncomfortable for me and the last few cycles, I have noticed that pads have made my skin incredibly irritated despite changing them all the time (no, not a yeast infection or anything... it goes away within a day or two of my period ending and not wearing pads).
Any suggestions for period undie brands or  pads that might not make my skin so irritated??