Question

The reason you read so many conflicting things is most of the authors are either stupid or lying. I mean that with all seriousness. There are some basic truths regarding physique change and muscle building, but since these truths don't sell expensive supplements, new workout gear, or require online coaching they are rarely conveyed.

The truth is that your size and physique is largely based on your genetics. If you chose your parents well, and they gave you only the best part of their DNA, then life is dandy and your physique is out of this world - without trying. Those people do exist, but it's not me... and sounds like it's not you either.

For the rest of us normal humanoids, we must rely on three basic things.
1. Nutrition
2. Training Intensity
3. Lifestyle (rest, sleep, work, relationships, etc.)

Because you are only 19 and have always been fit, my guess is that you have a fast metabolism and excellent insulin sensitivity (Hooray! Thank your parents.)
So, YES you can eat carbs but still keep them clean and strategic. Don't waste too much of that valuable real estate in your stomach on carbs.

In general, the insulin sensitive who are working to gain lean muscle should have carbs at least two times a day. Once upon waking up to break your fast from sleeping, and the second directly after your workout. Other than that it's discretionary.

Good carbs in the morning are potatoes or natural grains (i.e. non gmo rye bread or oatmeal)
Post workout should be as close to glucose as possible: dextrose, grapes, berries, honey, etc.

Other than that focus on good quality fat intake and bio-available proteins (i.e. eggs - raw is best)

Here's a weight gain diet my trainer, Vince Gironda, wrote about in his book The Wild Physique. Because you are only 110lbs, I would reduce everything by about 30%:

Breakfast

4-9oz. liver, chops, steak, hamburger, or fish
4-6 eggs or 4 oz. natural cheese
1 glass certified raw milk, half & half or raw cream
2 slices rye or whole-wheat toast with sweet butter

Lunch

Eggs (no limit)
Meat (any kind, no limit)
8 oz. cottage cheese
Raw vegetable salad
Fruit

Dinner

Same as lunch (choose different foods)
Yogurt
Fruit

Special Supplements

10 Amino-Acid and Desiccated Liver Tablets (every 3 hours)
5 Yeast Tablets (every 3 hours)
10 grams of arginine, ornithine (before retiring)
5 grams of tryptophan (before retiring)

Snacks

Half & Half
Vince’s Special Protein Drink
Between-meal sandwiches with cheese, eggs, meat, tuna fish, or peanut butter on rye or whole-wheat bread.
Vince’s special protein drink was as follows:

12 oz. half & half
12 raw eggs
25-50grams protein from powder
1 banana

The protein drink is typically sipped throughout the day.

So that's the food part. Again, because this was general advice for an average male in 1960 (probably 165lbs.) I would reduce it by 30% considering your current weight. Vince also liked using a lot of natural supplements that are typically very inexpensive. Enzymes, HCL tabs, and glandulars were among his favorites, and I use them still.

Next you must learn to train with INTENSITY!
Your body does not know if you did 5 sets or 2. 20 reps or 10. Your body responds to effort (how hard you work) and intensity (maximum work you can do in the shortest amount of time.) This means, you need to focus on giving your maximum effort in the shortest amount of time each time you train.

Since you played soccer, you should know that jogging for one hour produces a very different result compared to sprinting 100 yards with brief intervals of rest for 20 minutes.

The intensity of sprinting (all out maximum effort in the shortest amount of time) is what produces the amazingly muscular bodies found on sprinters. On the other hand there are plenty of skinny and fat joggers out there. No normal person ever got large, muscular legs from jogging.

So, this means you need to lift weights in a proper manner at maximum intensity. In the beginning you may be doing 5 sets of 5 reps to learn your limits and the mechanics of the movement. But optimally you'll be doing 1-3 sets total per exercise, 6-12 reps, 4-6 sets per body part, 10-30 seconds of rest between sets, and only training for 20-30 minutes per workout. Then go home.

REMEMBER! Training is only a stimulus, the response (recovery and growth) happens out of the gym.

So this brings me to part three, lifestyle.
You need to rest and recuperate from your training. Failure to do so will only hinder your progress and eventually cause injury.
You should reduce your response to stress (i.e. laugh rather than cry or get angry), and sleep as often as possible.
Enjoy life, and don't go back to the gym until you have not only recovered, but actually improved from your previous workout.

For some people this is 24 hours, for most people it's 48-72hours. For some of my hard gainers they train once a week. I had one kid who couldn't gain any mass until I got him down to training (again with INTENSITY) once every 10 days. Another mentor I am blessed to learn from, Mike Mentzer, spoke of a ectomorph trainee who trained once every 21 or so days... and his muscles finally grew ... a lot.

Good luck!