I’ve been working out eating better and haven’t lost much weight

My whole life I have been under weight I couldn’t gain weight if I wanted to I finally hit an age where I was eating more and started to finally gain weight I was a big late night eater soda drinker and fast food eater. About a month ago I cut all that out I drink nothing but water I eat a yogurt for breakfast a light lunch and dinner rarely eat bread if I do it’s low calorie and dinner is the last thing I eat I use to eat all the time around 11-12 pm sometimes full meals I gained a lot. The past month I kicked it up a notch been working out 6/7 nights a week weightlifting to tone my arms to workouts to lose weight ending in atleast 100 sit ups crunches star touches until my stomach is burning. It’s been a month I’ve lost 4 pounds my stomach is still huge I’m starting to have no motivation I use to drink a soda at lunch a soda after work I’d get Dunkin’ Donuts in the morning get a wrap and a chocolate milk and at night I’d always eat I now don’t eat after 7 pm what’s going on?? Really starting to lose hope might as well go back to what I was doing and already enjoy myself during this time