Stunna, welcome and thanks for the topic. I haven't seen any other questions you've posted, but I will address what I can here. Before I start anything, I will ask that you hold off on doing any kind of cycle - oral, injectable or SARMS. If you're looking to run an oral cycle then it's clear you haven't done the research necessary to begin using AAS. That's fine, that's why we're here. To make sure you not only reach your goals, but do so safely.
30 years old. 6'2". 140. Small and skinny your whole life. Daily Marijuana user. This is all the information your profile provides so I will run off this.
The perspective you have on nutrition needs to change. You are beginning with a weight gainer supplement and then trying to build a diet around it. Ideally, you'll want to establish a diet based in whole, high quality foods and then add supplements to it. Supplements are supplemental.
3500 calories is actually a good starting point. If you're training hard then I would not drop below this number. You're going to have to find a way to eat 5-6 meals a day. Let me run a very simple blueprint real fast.
Meal 1: 6 whole eggs, 1.5 cups of oatmeal, 1 tablespoon of honey.
Meal 2: 6 Oz ground beef, 1 cup of white rice
Train
Meal 3: post workout weight gainer shake
Meal 4: 6 Oz chicken breast, 1 cup white rice, 5 Oz broccoli
Meal 5: 6 Oz ground turkey, 10 Oz potatoes, 5 Oz spinach
Meal 6: 6 Oz ground beef, 2 tbspn peanut butter
I don't know the macros or calories of this but the protein is around 300, carbs around 400, fats around 150 maybe. That's going to bring you over 4000 calories. For a hard gainer like you, it may be exactly what you need.
Food is the most anabolic substance you can put in your body. Try eating like this for 60 days and training with the heaviest weights you can use for 6-10 reps and don't leave the gym until you're soaked through your tee shirt.
I also recommend getting a blood test done as Marijuana is notorious for lowering natural test production and I already suspect you may have Low T.
Nothing about the diet or training is going to be easy at first. But results are possible if you are relentless and committed.
God bless.