After changing my navbar to a full-width navbar, the width of my input div and ul with icons also changed. I have tried many solutions but am unable to fix the problem. I suspect that using a container to center the content in the navbar may be causing the issue.
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.1.0/css/all.css" integrity="sha384-lKuwvrZot6UHsBSfcMvOkWwlCMgc0TaWr+30HWe3a4ltaBwTZhyTEggF5tJv8tbt" crossorigin="anonymous">
<nav class="navbar-nav navbar-expand-sm fixed-top">
<div class="container">
<a class="navbar-brand"><img src="path1610.png"></a>
<div class="col-8 col-sm-6 col-md-7 col-lg-5 col-xl-5">
<form class="navbar-form">
<div class="input-group">
<input type="text" class="form-control" placeholder="Let's rock!">
<div class="input-group-append">
<button class="btn btn-outline-primary"><i class="fas fa-search"></i></button>
</div>
</div>
</form>
</div>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarHidden" aria-controls="navbarHidden" aria-expanded="false" aria-label="Toggle navigation"><span class="navbar-toggler-icon"></span></button>
<div class="collapse navbar-collapse" id="navbarHidden">
<ul class="navbar-nav ml-auto">
<li class="nav-item">
<a class="nav-link" href="#">
<span class="fas fa-user fa-2x"></span>
</a>
</li>
<li class="nav-item">
<a class="nav-link">
<span class="fas fa-bell fa-2x"></span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span class="fas fa-fire fa-2x"></span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span class="fas fa-cog fa-2x"></span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">
<span class="fas fa-comments fa-2x">
</span>
</a>
</li>
</ul>
</div>
</div>
</nav>