No one knows how you are going to feel on this cycle so just plan for the longest but cut it when you have had enough of the sides. I know for me, 8 weeks would be my max time with tren ace.
There is no best SARMs stack just like there is no best steroid stack. There are just a bunch of compounds that you can put together based on your goals. That will be "your best" stack.
Hopefully you ran a good PCT man. At your age, there was no need to run a stack like that. LGD dose was 2.5x higher than it should have been and S-23 is something I would not have recommended at all.
Steve has written about this in detail before but the basic outcome is that you need to run proviron (or any DHT) to prevent deca dick. Proviron is preferred because it is not liver toxic and is very mild.
You can do it from the standpoint that it is not suppressive but I would not recommend running any drug year round. Take 4 week breaks at minimum between 16 week runs.