"Could not connect to database"

For the life of me, I can't figure out why, but I can't connect to the database. MAMP says that my host is "localhost", my port is "3306" and my username and password are "root". I changed the information in the configure.php file. Nomatter what I do differently, I keep printing "Could not connect to the database." I don't know enough to narrow down what the problem could be. I've spent hours on this. I've changed ports, tried making a new user in myphpAdmin, I've used the mysqli_connect alternative not discussed in this tutorial. Yes, mySQL and Apache servers are on. I'm hoping this is trivial and that someone one here can swoop in and rescue me.

I must note that I didn't put the entire project in the htdocs folder. I'm working on my own project, so I removed the configure.php and database.php files and frankensteined them into my own project. I figured that it wouldn't make a different. I thought I'd still be able to connect to a mySQL db that I made. I just swapped out the name of the db for the shirt project with the one that I made. Please help. Here's the code:

<?php

try {
    $db = new PDO("mysql:host=" . DB_HOST . ";dbname=" . DB_NAME .";port=" . DB_PORT,DB_USER,DB_PASS);
    $db->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
    $db->exec("SET NAMES 'utf8'");
} catch (Exception $e) {
    echo "Could not connect to the database.";
    exit;
}