I am facing issue with pagination as its not working correctly. its droping records. could you please help me out.
Here is my code.

Apex class: 


public with sharing class SearchController{

    public integer PageSize {get;set;}
    public integer PageNumber {get;set;}
    public integer RecordCount {get;set;}
    public List<contactwrapper> objAWList {get;set;}
    private Set<id> selectedContactIds;
    public boolean displayPopup {get; set;}  
    public List<contact> objSelectedContacts {get; set;}
    private String soql {get;set;}  
      
    public SearchController() {
        PageSize = 10;
        PageNumber = 1;   
        RecordCount = 0;
        selectedContactIds = new Set<id>();
        objAWList = new List<contactwrapper>();
        objSelectedContacts = new List<contact>();
          
    }
      

    public void closePopup() {        
        displayPopup = false;    
    }     
      

    public void showPopup() {  
        setSelectedContacts();      
        displayPopup = true;    
        objSelectedContacts  = GetSelectedcontacts();
    }
      
    public Integer getSelectedCount(){
        return this.selectedContactIds.size();
    }
      
    public List<contact> GetSelectedContacts(){    
        List<contact> objConList = [Select Id, Name,Email,Account.Name,Account_Cust__c,Job_Title__c 
                                    From Contact Where ID IN : selectedContactIds];       
        system.debug('objConList :'+objConList);
        return objConList;
    }
      
      
    private void setSelectedContacts()
    {
        for(contactwrapper item: objAWList)
        {
            if(item.IsSelected)
            {    
                if(!this.selectedContactIds.contains(item.ContactId))
                {
                    this.selectedContactIds.add(item.ContactId);
                }
            }
            else
            {
                if(this.selectedContactIds.contains(item.ContactId))
                {
                    this.selectedContactIds.remove(item.ContactId);
                }
            }
        }        
    }
      
    public integer PageIndex {
        get { return (PageNumber - 1); }
    }    
      
    public integer PageCount {
        get { return getPageCount(); }
    }
      
    public integer Offset {
        get { return (PageSize * PageIndex); }
    }
      
  
    public void runSearch() {
        objAWList = new List<contactwrapper>();
        try {
                List<Contact> objConList = new List<Contact>(); 
                String contactName = Apexpages.currentPage().getParameters().get('ContactName');
         
                if (!contactName.equals('')){
                    soql = 'select firstname, lastname, Name,account.name,Job_Title__c,Account_Cust__c from contact where account.name != null';
                    soql += ' and name LIKE \'%' + contactName + '%\'';
                    soql += ' order by firstName ASC limit '+PageSize +' offset '+Offset;
                    system.debug('soqlfinal::'+soql);
                    objConList = Database.query(soql);
                    RecordCount = objConList.size();
                    
                }else if(contactName.equals('')){
                    RecordCount = objConList.size();
                    objConList.clear();
                }
          
                 system.debug('objConList---'+objConList);                    
                 if(!objConList.isEmpty()){                         
                     for(Contact Con : objConList){
                            ContactWrapper objAW = new ContactWrapper();
                            objAW.ContactId = Con.Id;
                            objAW.ContactName = Con.Name;
                            objAW.AccountCust= Con.Account_Cust__c ;
                            objAW.JobTitle= Con.Job_Title__c;
                            
                            if(this.selectedContactIds.contains(con.Id)){
                                objAW.IsSelected = true;
                            }
                            else{
                                objAW.IsSelected = false;
                            }
                            objAWList.Add(objAW);
                     }
                 }             
             
        }
        catch (QueryException e) {
            ApexPages.addMessages(e);   
            
        }
    }
      
    public integer LNumber {
        get { return RecordCount == 0 ? 0 : (Offset + 1); }
    }
  
    public integer UNumber {
        get { 
            integer iUNum = ((LNumber + PageSize) - 1);
            return (iUnum > RecordCount) ? RecordCount : iUNum; 
        }
    }
      
    public boolean AllowMoveNext {
        get{ return ((PageIndex + 1) < PageCount); } } public boolean AllowMovePrev { get{ return (PageIndex > 0); }
    }
      
    public void Prev() {
        setSelectedContacts();
        PageNumber--;
  
        if (PageNumber <= 0) { PageNumber = 1; } } public void Next() { setSelectedContacts(); PageNumber++; if (PageNumber > PageCount) {
            PageNumber = PageCount;
        }
    }
      
    public void Last() {
        setSelectedContacts();
        PageNumber = PageCount; 
    }
  
    public void First() {
        setSelectedContacts();
        PageNumber = 1;
    }
      
    private integer getPageCount() {
        integer iPageCount = 1;
  
        if (RecordCount != 0 && PageSize != 0) {
            iPageCount = (RecordCount/PageSize) + ((Math.mod(RecordCount, PageSize)) > 0 ? 1 : 0);
        }
        return iPageCount;
    }
      
    public class Contactwrapper
    {
        public Id ContactId {get;set;}
        public String ContactName {get;set;}
        public String AccountCust {get;set;}
        public String JobTitle {get;set;}
        public Boolean IsSelected{get;set;}
        public Contactwrapper()
        {
    
        }
    }    
}