Hi! @Crazy_Ass_Girl

Thanks for voting and for requesting for a book review. I haven't read or critiqued books in a while and I hope this will be of some help. Note that I don't sugarcoat my reviews, but expect them to be helpful and constructive, instead of just being overly harsh or critical, or too general that it didn't do anything to help you improve as a writer.

Moving on!

So you asked that I critique your ongoing story 'Our Journey'. I have read your first chapters and now I'm publishing this critique which should serve as a guide to help you improve your writing skills.

POINTS of FOCUS:  PLOT, GRAMMAR, DIALOGUE

COVER:

the cover looks okay. 

maybe the font style and size could be changed since the part saying 'A Story By' isn't legible. 

also, some splashes of color could make your cover more attractive so you could grab the attention of the readers searching for new teen fics/stories to add to their reading list.

BLURB:

mostly well-written and interesting premise.

there were some punctuation errors but they're very minor. :)

e.g.

Natalie Mattson, the daughter of the well-known investor Dylan Mattson, was perfect. 

PROLOGUE:

the prologue was short and served its purpose, i think. it gave some intrigue/mystery and caught my interest. there were a few issues with sentence construction and punctuation but they're very easy to fix. :)

e.g.

I answered it after a second of hesitation. "Hello?" I asked in a muted voice, uncertain of this mysterious phone call's intention.

*insert paragraph break*

A pretty girl like you shouldn't be walking in the night all alone," answered a cold and thick male voice on the other end, sending a shiver down my spine.

I spun, scanning my surroundings for anyone around. "Who are you?" I asked, trying to sound tough, but he had already ended the call.

1st chapter:

In the first part, the paragraphs lacked scenic descriptions and I couldn't imagine the setting. Although there was some character building involved,  I couldn't quite visualize the characters and their reactions due to the lack of descriptive imagery in the narration. The common creative writing rule of  "showing more and telling less" would be applicable in most parts. 

Some punctuation errors were a bit distracting but I guess that's just my inner Grammar Nazi talking :)  
Still, proofreading this can help improve your narration, and would definitely be something your readers will appreciate about your work.

Some edits I suggest:

"...a few minutes ago," I said, tears pooling in my eyes.

"Aren't you supposed to know?" Mom glared at me. ('mom glared' can't be used as a dialog tag so the first part of the sentence, which is 'Mom', should be written in uppercase.

On the other hand, I got low grades no matter how much I studied, had a limited amount of friends, and barely knew how to do anything other than solving mystery puzzles.

"How am I supposed to know? (don't use two or more types of punctuation at the same time) I wasn't in the house when she left," I complained. ('I complained' is a dialog tag so a comma would be more appropriate before the closing quotation marks) Then it hit me. "Wait-- I have an idea. She might be at Landon's party!"  (omit 'I exclaimed' because the tag would make this part redundant since you've already used the exclamation point after her dialogue)

*insert paragraph break*

"Well, then. Call Landon. We'd really want to see your sister come home safe." Father scowled at me fiercely. (try reading the dialogues aloud. if they don't sound natural, scrap them or revise)

 *insert paragraph break* 

"Yes, Father," I said, looking down.

Despite our differences, Natalie and I loved (tense switch from past to present) each other so much and treated each other with compassion. She always helped (tense switch) me with homework and thoroughly explained things I didn't understand. Without my big sis, I didn't (tense switch)know what I'd do. She had(tense switch) trouble 

So we usually spent (tense switch)  time playing with puzzles.

Landon was (tense switch) Natalie's closest guy friend. 

**This is another part where the narration info-dumped. Try to lessen this in the first chapters. You could try incorporating the main characters' backgrounds and relationships with the other characters  in a subtler way, little by little in the next chapters, instead of telling the reader everything about the characters' personal lives in just one big group of 'telling' paragraphs. 

DIALOGUE:

"Nat! We were so worried!" My mother wailed. ('wailed' can't be used as a dialog tag so capitalize 'M' in "My mother") 

*insert paragraph break every time another character speaks/reacts*

"Don't ever pull that stunt on us again." Father came forward to embrace both of us. 

"Where were you?" Father was yelling again. "You made us worry. And your sister didn't know where you were." Father gave Diane the stink eye.   (Notice I changed up the dialogues a bit; some parts didn't sound realistic and natural.)

Instead of overemphasizing their parents' dislike for Diane through lengthy and sometimes unnatural-sounding dialogue, you could include the characters' descriptions and reactions in the narration.

Write the imagery in a detailed manner that will show their emotions and personality more effectively, instead of just telling the reader what the parents think about Diane and Natalie or how they feel about their daughters.

Some parts could use paragraph breaks so the readers on mobile won't be daunted by the huge chunks of narrative paragraphs in the first chapters. 

What I appreciated was the character-building and your willingness to improve your work. There were some issues with spelling, punctuation, and tense consistency, but with some proofreading, I'm fairly certain you'll be able to polish off the chapters in no time. 

Good luck!

Hope this helped.

Your friendly critic,

M