Well we have some varying opinions here. What I do want to note before I state my opinion is that you need to find something that works for YOU. That is the most important thing.
Now, is push/pull a good routine? Absolutely, i have used that often in the past and grew like a weed. Do you have it set up correctly? From what you described, no. Your legs and back should not be trained on the same day, those are very large muscle groups that take a lot out of you and if done on the same day one will suffer without a doubt.
Do this instead...
Chest/shoulders/Tris
Legs
Back/shoulders/bis
Rest
Repeat
1 or two days rest depending on how you feel.
There is no problem training muscle groups twice a week, in fact, if on gear and getting the proper nutrition and rest you will grow faster doing this. With doing the split how I layed it out youd hit every muscle group twice in 8 or 9 days. And contrary to what a lot of people think training a muscle when it is sore (MILDLY SORE) is ok. With that said if you feel your muscles are TOO sore from training, like sore to touch youve trained to hard and done too much damage, when muscles see such trauma they will build up scar tissue to 'heal' faster. NOT what you want.
Also, exercises amd the order you performs them is is key as well. You want your workouts to make sense not have just a bunch of shit thrown in where ever.
Of course push/pull will not work forever and youll have to eventually switch things up, which is how we continue to grow. But I am a firm believer in push/pull and have built a lot of muscle with that set up.