Kellie - You can usually tell if bub is dummy sucking by whether or not you can hear them swallowing anymore. When they first latch on you will hear strong sucking and swallowing noises, sometimes when they're done they just like to have a little suck, but not feed. Generally babies can feed efficiently anywhere from 5 - 15 minutes per side so if you find Tahlia is going more than 15 minutes on one side you could unattach her and put her on the other side, then unattach her again at the end. I had to do this with Kieran in the early days (recommended by a MCHN) and he quickly got the idea. You've probably already worked it out, but to unattach bub without hurting yourself you can put a finger in between bub's mouth and your nipple to break the seal.