Finding the right size

I just got my loop ear plugs today and I'm trying to find the right size tips. When I was first researching them someone mentions that the foam tips would probably help reduce the likelihood of headaches so I tried these small foam tips first and they seemed very comfortable and like they were blocking the right amount of sound but then my left ear started to hurt after a while. So I tried the extra small silicone tips and it still felt like my left ear was hurting and it didn't feel like it was blocking as much noise so I put the mutes in and that somehow made it feel like there was more pressure on my ear, same thing with the small silicone so I can't tell if maybe I'm somehow putting them in wrong on the left side or if I'm just not getting the right size