I suggest you learn from the past generations of bodybuilders. Back in the day when they had no sophisticated equipment, no Internet recommendations, and no nutritional supplements, those who wanted to get stronger and grow muscle had to bust their butts with hard work to achieve strength and size gains. They had only the basic means of stimulating muscle tissue - barbells and dumbbells - and the smarts to allow for proper rest and recovery following their training.
It still works today. But the simplicity of hard work has either been blurred or completely lost from all the fancy stuff that pervades our current training culture. So, if it still works, why don't you try "old school" and give it a go? Working hard is still the way to go.
Let me tell you about a simple but very difficult program for increasing lower body strength and facilitating weight gain. The 20-rep barbell squat routine. It works. But it is brutally difficult.
Here's how it works:
Train your lower body twice per week. One session is the 20-rep squat routine and the other is something different like deadlifts or leg presses.
Select a resistance that you would normally use for a tough set of 12 repetitions. With that resistance, perform 20 repetitions. Sure, it's going to be challenging but find a way to squeeze out 8 more reps to get to the 20-rep goal. You can do it if you focus on the task at hand. Catch your breath between reps and concentrate on getting one rep at a time.
Now that you have gutted it out to achieve the 20-rep goal, don't celebrate too hard. It's time to do more. Given proper recovery time, your body will adapted to the previous 20-rep stress and can now tolerate more. You did it, your body adapted to it, now you are able to do even more.
For the next 20-rep squat workout add at least five pounds to the bar (10 pounds maximum). Your goal again is 20-repetitions.
If you give it all-out effort you'll accomplish it. Remember, you only added a few more pounds from the previous successful session so be confident you will achieve the 20-rep goal.
Try it for 8 weeks. It's inevitable that you will eventually hit a wall and won't be able to progress anymore, but you'll be surprised how much you will accomplish in such a short time and the gains will be amazing.