Besides your diet you will need to add a mass gainer to your supplement stack, most mass gainers contain protein, carbs and creatine, the stuff that makes you grow so make sure you up your protein and carb intake so that you can flood those muscle with the stuff it needs to grow, like Black Bull Huge AF Massgainer.
When it comes to training get yourself a training partner, it helps to stay motivated and when you want to grow you will need to lift the big plates so a spotter will be beneficial, your girlfriend is not a training partner, let her to yoga or something and leave the growing to the men. Stick to basics, bench press, dead-lifts and heavy squats should always be part of your training program and for f*cksakes train your whole body, calves, abs even forearms should be trained just as hard and any other muscle. Mix things up by changing the days you train certain muscles, I know Monday is considered INTERNATIONAL CHEST DAY, but if your goal is to be bigger and badder than the average guy in the gym you are going to have keep your body guessing.
And the secret weapon, SLEEP!!!!! If you pounding the plates you’ll be putting your body through a lot so make sure you get enough rest and sleep to allow your body to grow. Here is a little cocktail that will volumize cells and help you recovery while you get your well deserved beauty sleep 4 capsules ZMA +5 grams creatine +5 grams L-glutamine with 1.5L water. You will wake up feeling like a bronco bull.