If you arent progressing in the gym then look at 4 things.
1.Programming-Your program doesnt work
2.Nutrition-Your not eating enough to support the demands you are making on your body so it can grow.
3.Rest-Your not resting enough to recover. Lack of sleep, stress in your life,etc.
4.Effort-Your not putting in the effort required to progress. This could also be due to motivation.
If your not progressing analyze these four factors and you will usually find your answer. If its a couple of bad workouts its usually not the programming but one of the other three. If your well rested, fed, and fired up to train and you cant progress for weeks then maybe look at number one.
Lastly, you will make gains on a program like Korte or Sheiko but its not optimal or necessary. Your at a point where you can add a rep or 5 pounds on at least a weekly basis. The longer programs are designed for a more advanced athlete who needs to take months in hopes to see a 10 pound increase.
I would stay with SS and your goal is to add at least one rep per workout. Got 225 for 1x5, 1x4, and 1x3 the last workout? You have to at least go 225 for 5,5,3. Once you have made your 3x5 then add 5 pounds and go again. If you can do more do it but one rep at a time is progress, and will end up in huge gains over a long span of time.