Removing fragment from backstack on click of navigation drawer item

In my app I have a navigation drawer with several fragments. One of the menu from navigation drawer is for closing current visible fragment and go to previous one. To achieve above behavior I added fragment to backstack.

This is how my fragment transaction looks like

if (fragment != null) {
        fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.container_body, fragment, "name");
        fragmentTransaction.addToBackStack(fragment.getClass().getSimpleName());
        fragmentTransaction.commit();

        // set the toolbar title
        getSupportActionBar().setTitle(title);
    }

I have added onBackPress() method to handle backstack transactions. Here is the code for backpress method.

@Override
public void onBackPressed() {
    if (fragmentManager.getBackStackEntryCount() > 0) {
        Fragment fragment = getSupportFragmentManager().findFragmentByTag("name");

        fragmentManager.popBackStack();

        if (fragment instanceof Articulos) {
            mToolbar.setTitle("Articulos");

            // add your code to change title of toolbar
        } else if (fragment instanceof Clientes) {
            mToolbar.setTitle("Clientes");
        } else if (fragment instanceof Pedidos) {
            mToolbar.setTitle("Pedidos");
        } else if (fragment instanceof Herramientas) {
            mToolbar.setTitle("Herramientas");
        } else if (fragment instanceof Visor) {
            mToolbar.setTitle("Visor");
        }

    } else {

        super.onBackPressed();
    }
}

onBackPressed() method works properly as required when called on press of device back button . From navigation drawer menu for removing fragment from backstack, I have called this same method there also like this.

case 5:

            title = "Cerrar";
            onBackPressed();

            break;

PROBLEM: My problem is that when I call onBackPressed() from navigation drawer, it only pop first fragment from the backstack and not the remaining ones. I debugged this method and it is getting called properly but fragments are not changing after first time. I tried with popBackStackImmediate too but problem still remains. What can be the problem here?