Look man before you use AAS first most of important is that you need to get your diet down man. You lost all of your gains mostly attributing to a poor diet. Warranted that you will not retain all of your gains from testosterone but you can retain a good amount of it if your diet is good.
Here are some great bulking foods/liquids that I suggest:
Chicken
Lean Beef
Eggs
Peanut Butter
Chocolate Milk
Oats
Pasta
Potatoes
Raw Honey
Tuna
Supplements Worthy of Spending Money On:
waxy maize starch/dextrose - Take 30-35grams of dextrose after working out. This will spike insulin levels feeding more carbohydrates into your muscles and leaving protein within the muscle. Dextrose is more fast acting than waxy maize starch. Waxy Maize Starch is like a longer acting dextrose within the body. Dextrose is like the Whey Protein for sugar or glucose while waxy maize starch is like milk protein.
MRP-Protein-Creatine-Glutamine-BCAA-WATER
Protein should be a gram to a gram and a half per each pound of body weight. Creatine should be taken at 10 grams split in two doses throughout the day. It is recommended to take a gallon of water minimum a day because the creatine will store the water into the muscle giving more lubrication and thus making your weights go up a little bit.
flax seed oil
Also grapefruit juice is known for enhancing the bioavailability conversion of supplements and may not be a bad idea to add this in if your very serious about gaining weight.