Why is my elastic search query not returning all elements in the elastic search db

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C#4.0

Elasticsearch

I have this mapping and settings:

PUT loalhost:9200/persondb
{
    "settings": {
        "analysis": {
            "filter": {
                "autocomplete_filter": { 
                    "type": "edge_ngram",
                    "min_gram": 2,
                    "max_gram": 15
                }
            },
            "analyzer": {
                "autocomplete": {
                    "type": "custom",
                    "tokenizer": "whitespace",
                    "filter": [
                        "lowercase",
                        "autocomplete_filter" 
                    ]
                },
                "rock_field":{
		    "type": "custom",
                    "tokenizer": "whitespace",
                    "filter": "lowercase"
                }
            }
        }
    }
}

PUT localhost:9200/persondb/userData/_mapping
{
    "userData": {
        "properties": {
            "FirstName": {
                "type":            "string",
                "index_analyzer":  "autocomplete", 
                "search_analyzer": "rock_field" 
            },
			"LastName": {
                "type":            "string",
                "index_analyzer":  "autocomplete", 
                "search_analyzer": "rock_field" 
            },
			"CurrentCompany": {
				"type": "string",
				"analyzer": "rock_field"
			},
			"CurrentLocation": {
				"properties": {
					"City": {
						"type": "string",
						"analyzer": "rock_field"
					},
					"Country": {
						"type": "string",
						"analyzer": "rock_field"
					},
					"State": {
						"type": "string",
						"analyzer": "rock_field"
					}
				}
			},
			"ProfileTitle": {
				"type": "string",
				"analyzer": "rock_field"
			}
        }
    }
}

http://localhost:9200/user/search passing this query string = {"q":"san"}

When I run this query from POSTMAN am getting this results with only 2 elements

[
  {
    "Id": "57236cbe80eed110c8b739f5",
    "Score": 0.7097881
  },
  {
    "Id": "5739d95d80eed7100c32a59d",
    "Score": 0.48913243
  },
  {
    "Id": "57332dec80eed60a0492b68e",
    "Score": 0.3120335
  },
..
.....


]

Why am I not getting all the data elements in the elasticsearch db
as in the mapping?
thanks for your help.

What I have tried:

localhost:9200/persondb/_search
when I run this query It returns the 10 hits with all the data elements>

{
  "took": 3,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 602,
    "max_score": 1,
    "hits": [
      {
        "_index": "persondb",
        "_type": "userData",
        "_id": "567855bcd5eae9184c833993",
        "_score": 1,
        "_source": {
          "FirstName": "Kishore",
          "LastName": "Rajendra",
          "ProfileTitle": "default",
          "CurrentLocation": {
            "Country": "India",
            "ZipCode": null,
            "State": "Karnataka",
            "City": "Bangalore",
            "Region": null,
            "Verified": false
          },
          "CurrentCompany": "Rock LLC",
          "Project": [
.
.
.