Welcome to the board! If your lower stomach is your "worst" area, it will seem like it's making the slowest progress. Everybody has certain areas that respond easily and others that take more time and effort.
Even though you're concerned about your abs, be sure to train all your body parts, even the ones you think are fine. It's important for preventing injury, plus you'll develop a stronger leaner more aesthetically balanced physique.
As for diet, that's really the biggest piece of the puzzle. I used to think I could just work out harder, but that'll only get you so far. The neat thing about a training diet is it's a completely different mindset from the traditional weight loss diet.
A typical weight loss diet is all about deprivation and restriction. With a training diet, the focus is on getting sufficient calories and nutrients to support your training and maintain muscle mass, since muscle is metabolically active. When your body is sufficiently nourished, you feel better and can train at a higher intensity and burn off the fat.
I like sweets too, and I still eat them. The cravings for them are gone now that I'm eating small meals every 2-3 hours (each w/ some protein).