Extjs Infinite grid loading only first page or all of them at once

Question

I have added an infinite scrol grid in extjs 4.2.2, and proxy looks as below,

 setProxyForGridStore: function () {
        var me = this;
        me.proxy = Ext.createByAlias('proxy.search-results', {
            reader: {
                type: 'json', root: 'maingridrows', totalProperty: 'total'
            },
            url: Premier.helper.Common.getActualUrl('/tools/get-all-notes'),
            extraParams: {
                criteria: Ext.encode(Premier.model.search.Query.getQueryData(me.queryObj))
                , notesSearchId: me.queryParams["notesSearchId"]
            }
            //,
            //type:'ajax'

        });
        me.down('#notesGrid').store.setProxy(me.proxy);
    },

and my response looks as below,

by default iam getting only one page . I should be able to scroll and get respective page based on scroll position.

pagesize is 15 and storing load as below,

store.load();

Store is defined as below,

 var store = me.store = Ext.create('Ext.data.Store', {
            fields: [
                'NoteType', 'EntityName', 'LastEditedDate', 'NotesChildViews'
            ],
            pageSize: 17 ,//buffered: true
        });

If buffered config is added to store,then it is loading all the pages at once . but I need to get the page based on scrolling. What am i missing?