Not every workout always has to make you sore to be effective. Having said that, if you haven't lifted anything heavier than a gallon of milk in awhile, you should be sore from an effective workout. I'm guessing you're not working muscles sufficiently to fatigue with only 6 reps for 2 sets. Move up to at least 10 reps per set, and do at least 2 different exercises for each body area you work on that day. So for example, if you're going to work on legs that day, do 2 sets up 10 squats, and 2 sets of weighted lunges (10 on each leg). Many of us on this forum really like the New Rules of Lifting for Women (NRLW), and that book does a terrific job of laying out a progressive program that works. Good luck and stick with it!
You don't drown in the river by falling in, but by failing to get back up.