At 6' 170 you are not genetically maxed, not a chance. You having a fast metabolism or being a 'hard gainer' does not mean your genetically maxed. You not being able to get past 170 can be due to a number of different things. The MAIN thing being nutrition. You either aren't eating enough or, you aren't eating enough of the right foods. And, although at one point in my journey I though it was all about overall calories and macros, I have since realized it goes far past that, so just cramming in a shitload of food isn't going to do a thing if your body cant break those foods down, absorb them and utilize them as best it can.
You can eat all you want but if you aren't able to utilize those foods you are eating by digesting them properly then everything is a waste of time. So, get the nutrition dialed in. Eat your proteins, fats, and carbohydrates but, make sure to get plenty of micro nutrients in as well from veggies and leafy greens to help digestion of the macronutrients. Get fiber in take where it should be and go get yourself a digestive enzyme to aid in digestion.
Aside from that being the main cause, the next thing is possible over training IMO, and I know some guys say 'overtraining' is bullshit but its not, you can even over train while on gear as far as Im concerned . I have no idea how you train (how many days a week and for how long) but, if you have a crazy fast metabolism I would train less. You don't really need to decrease frequency but possibly decrease volume allowing you to not damage the muscle too much and allowing your body to heal faster. You don't need to go into the gym a blow everything out to the point youre crippled, or even sore the next day to grow. Fast metabolism+training too much=not growing how you should. All it is, is a catch up game if this is the case.
Lastly, I would look at your Total Testosterone levels, LH and FSH levels through a blood test to see where those sit. You stated you ran a few cycles now....but have you recovered? Running cycles upon cycles without ever properly recovering is going to leave your natural Testosterone production tanked most likely and that in itself could be another reason you aren't gaining weight. Doing PCT doesnt mean you recover, it means you did PCT....that's it.
I don't really see a need to extend the cycle an extra 2 weeks with a different ester. And the PCT timing is off. 2 weeks is not enough time to allows the hormones to leave your body. Wait 4 weeks with Sustanon as it has the long Decanoate ester in it which has a apparent half life of 15 days. Starting PCT too soon will equal a failed PCT. And run Nolvadex along side the Clomid, it will improve chances of recovery.
Thanks for the wealth of info here. Going to check into the blood work,been tired and have had a healthy appetite my whole life so possible that I've always had low T. Thanks for the cycle advise as well.