You should be gaining weight. And increasing your lifts.
I completely, utterly have no bloody idea what the term "bulk" means nowadays, so let's just use the term "gain".
The objective is to gain muscle mass while minimizing fat gain.
This is done by:
A. Eating in a reasonable caloric excess.
B. Increasing strength in the major lifts.
Generally, a good physique will require a strength to bodyweight ratio of at least:
Bench: 1.4 times bodyweight
Squat: 2 times bodyweight
Deadlift: 2.2 times bodyweight
Give or take subject to individual leverages and genetics.
This is achieved through:
- Using common sense
Use the mirror and the scale to gauge progress weekly. Always strive to break strength PRs.
If you gain 5lbs in a month but your bench goes up by 3lbs, you're getting fat.
If you gain 20lbs in 1 month for no rhyme nor reason just to make the scale move, you're getting fat. And you're fucking stupid.
BUT If you are a genetic outlier and can gain 20lbs in 1 month while increasing your bench by 100lbs, don't change what you're doing just because everyone else says what you've done is impossible.
- Consistancy in your diet
Develope good eating habits at fixed intervals in a day. Do not skip meals. Use a calorie tracker like Myfitnesspal and hold yourself accountable to meeting caloric targets.
- Intensity in the gym
Don't just move the weights around. Explode the weight up and lower under control. See CT's "The Perfect Rep" article.
- Do not have any pre-conceived notions of your bodytype and genetics.
Understand that we all fall on a bell curve when it comes to genetics.
A true hardgainer is as rare as an IFBB Pro. Most of us fall somewhere in between.
If you are not gaining it's almost always due to a lack of consistancy or effort in your diet or training.