porcelain tile project problem

This is my first time laying tile. I am laying 6x24 porcelain tile in a 5x4 entryway and using TEC Ultimate large tile mortar. I got 4 and a half rows done last night and this morning I noticed a lip on the last two that I laid that I'm not happy with so I decided to take them up and re-lay them. They came up way too easy and there was little to no mortar on the back of them. I decided to take up another tile which looked the same as the first two. It took me 4 hours to lay those 4 1/2 rows (what can i say. I'm a beginner and it was more complicated than I expected it to be.) I'm wondering if my mortar got too dry towards the end and that's why the tiles didn't seem to adhere or if there could be some other problem. I made sure to push them around a little and pushed them down good when installing them . I haven't taken up the rest of them but am prepared to do so If I need to. I want to do it right and I'm just not sure how to proceed from here. Any advice would be greatly appreciated. I'll try to attach a couple pictures. Thank you