Am I missing something here? 5x5 is widely recognised as a solid routine, and I know I personally could never stand doing 5/3/1, especially as a beginner... why anyone still learning the lifts would practice only once a week is beyond me. I realise OP said he liked Wendler's article then proceeded to ignore it, but aside from that I'm not sure what's wrong here.
As for the "problem", I say stop being pathetic and increase weights as recommended. 4th-5th reps are hard? Good, that's kinda the point. Don't tolerate weakness, just keep pushing and learning and stop worrying about programs and diet so much. If you don't get all 5x5, keep going with the same weight until you do. There's no shame in failing, as long as you stay tight and don't mess up your technique too badly.
If I remember correctly, Stronglifts has bent over rows as a main lift; I say drop them and instead do 2-3 machine or dumbbell based exercises for back / biceps. You need your lower back for the frequent heavy squatting, and it's easy to become lazy and get injured when rows have exhausted your back. Pullthroughs with the low cable and GHD back extensions are far better options if you like extra lower back work.
You should easily (this is relative I guess) get to 140kg squat, 100kg bench, 60kg overhead, 150kg deadlift without resorting to anything more complicated. Eventually you may decide you prefer ramping your 5x5, and possibly moving to twice a week frequency, but you can certainly stick with this program for at least 4-6 months.
Diet shouldn't be too hard to get to grips with at this stage, just allow yourself unlimited quantities of foods that are mostly protein (eggs, meat/fish, etc.) and vegetables, and then increase or decrease carbs and fats based on progress. I assume you want to gain a decent amount of muscle, so start off with these reasonably high (for you), and adjust down if you feel you're gaining too much fat.