I find shaking fat, for me, is easier than gaining muscle. Regular, intensive work outs combined with counting and logging your caloric intake will lead to weight loss. It’s easier said than done, but it really is simple maths. Weight loss, if that’s what you want, really is all about motivation and determination.
For gaining muscle, I’d try Stronglifts 5x5 if you haven’t already. Yes, it involves squats and deadlifts but if you do it right, study the instruction videos and don’t try to rush the progression, you should be fine. Last time I tried it, I rushed it on squats and deadlifts, and I’m still paying the price. However, I have previously found deadlifts in particular to be very helpful for lower back issues.
Doing both at the same time is difficult, I find. To gain muscle, you need a caloric surplus and it’s hard for me to find the right balance. However, I’d say focusing on muscle gain will probably get you closer to the physical result you probably want. If you can, try to add a cardio day to your 3/week Stronglifts routine and see how it works.