Right now you need to get your diet in check. Do that first, help yourself maximize the HUGE amounts of testosterone you already have in your body, exercise powerfully, THEN move onto steroids later. Here is an example of what will happen if you start taking testosterone now:
Let us assume your test level is about 800, a good high number due to your age. If you inject testosterone into your body, the first thing it does is STOP making its own testosterone. While it varies for everyone, let us say injecting 200mg of test will give you around a test level of 800. What this means is you will NEED to inject 200mg of test JUST TO GET TO WHERE YOU CURRENTLY ARE NATURALLY. I made that in all caps because that is what is so important. To actually RAISE your level, you will need to add even more test in your injections. The next 300mg of test is the only part actually doing anything...you are literally wasting nearly half your gear.
You will certainly see gains, sloppy gains, but gains nonetheless. Then you will enter PCT and lose half of what you gained. You will also feel like crap, be depressed, and have no energy. In a month or two, you will recover and be back at where you started with a little more muscle - but nothing huge or significant.
Your diet is the key, get that in shape first. Do Keto or Carb Cycling and get your body fat down to a level worthy of using steroids (you are WAY too fat to use them now). Until you can drop below 15%, steroids will not do much help for you - but they can cause you a lot of harm.
My advice, stay away from the drugs. Get your diet fixed, hit the gym with the same desire you normally reserved for sex. Get your body fat down and THEN talk to us again. Hit the Diet Forum for help with the diet.