Pagination MySQL PHP

I'm trying to use pagination for a customer table using PHP, MySQL & Bootstrap. I wrote this code:

<div class="container mx-auto">
<!--Add class table-responsive for responsive table -->
<table class="table mx-auto">
    <thead>
    <tr>
        <th>Name</th>
        <th>Surname</th>
        <th>Email</th>
        <th>Phone</th>
        <th>Address</th>
        <th>Zipcode</th>
        <th>City</th>
        <th>Company</th>


    </tr>
    </thead>
    <tbody>
    <ul class="pagination">
        <?php
        if(isset($_GET['page'])){

            $previous = $_GET['page'] - 1;
            if($previous = -1 ){
                $previous = 0;
            }
            if($previous = 0){
                echo '<li class="page-item"><a class="page-link" href="#">Previous</a></li>';
            }
            else{
                echo '<li class="page-item"><a class="page-link" href="?page='. $previous.'">Previous</a></li>';
            }
        }
        $page_max = 10;
        $entriesInDatabase = $database->getData("SELECT count(id) FROM customers");
        $numberOfPages = ceil($entriesInDatabase['count(id)']/$page_max);

        for($i = 0; $i < $numberOfPages; $i++){

            echo '<li class="page-item"><a class="page-link" href="?page='. $i . '">'. $i. '</a></li>';
        }
        if(isset($_GET['page'])) {
            $page = $_GET['page'];
            $start = $page * 10;
            $end = ($page + 1) * 10;
            var_dump($start); 
            var_dump($end);
        }
        else{
            $page = 0;
            $start = $page * 10;
            $end = 10;
        }

        $customers = $database->getUsers("SELECT * FROM customers LIMIT $start, $end");

        ?>
        <li class="page-item"><a class="page-link" href="#">Next</a></li>
    </ul>
    <?php



    foreach($customers as $customer){
        $name = $customer ['name'];
        $surname = $customer['surname'];
        $email = $customer['email'];
        $phone = $customer['phone'];
        $address = $customer['address'];
        $zipcode = $customer['zipcode'];
        $city = $customer['city'];
        $company = $customer['company'];
        $id = $customer['id'];
        echo "<tr>
                <td>$name</td>
                <td>$surname</td>
                <td>$email</td>
                <td>$phone</td>
                <td>$address</td>
                <td>$zipcode</td>
                <td>$city</td>
                <td>$company</td>



              </tr>";
    }
    ?>

I want each page to show 10 records from the database so giving a limit to my SQL query. What happends now is the following; page 0 shows 10 records, page 1 shows 20 records, page 2 shows also 20 records but page 9 shows 11 records.

Could anyone help me out fixing this issue?