insert and remove fragments into viewpager properly

I'm making an adroid application with viewpager and fragments. I want to make an option to add or remove fragment pages to the pager dynamically. I have a custom FragmentPagerAdapter:

public class MyAdapter extends FragmentPagerAdapter implements TitleProvider{

    protected final List<PageFragment> fragments;

    /**
    * @param fm
    * @param fragments
    */
    public MyAdapter(FragmentManager fm, List<PageFragment> fragments) {

        super(fm);
        this.fragments = fragments;
    }

    public void addItem(PageFragment f){
        fragments.add(f);
        notifyDataSetChanged();
    }

    public void addItem(int pos, PageFragment f){
        for(int i=0;i<fragments.size();i++){
            if(i>=pos){
                getSupportFragmentManager().beginTransaction().remove(getSupportFragmentManager().findFragmentByTag(getFragmentTag(i))).commit();
            }
        }
        fragments.add(pos,f);
        notifyDataSetChanged();
        pager.setAdapter(this);
        pager.setCurrentItem(pos);

    }

    public void removeItem(int pos){
        getSupportFragmentManager().beginTransaction().remove(getSupportFragmentManager().findFragmentByTag(getFragmentTag(pos))).commit();
        for(int i=0;i<fragments.size();i++){
            if(i>pos){
                getSupportFragmentManager().beginTransaction().remove(getSupportFragmentManager().findFragmentByTag(getFragmentTag(i))).commit();
            }
        }
        fragments.remove(pos);

        notifyDataSetChanged();
        pager.setAdapter(this);
        if(pos<fragments.size()){
            pager.setCurrentItem(pos);
        }else{
            pager.setCurrentItem(pos-1);
        }
    }



    @Override
    public Fragment getItem(int position) {
        return fragments.get(position).toFragment();
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    @Override
    public int getItemPosition(Object object)