Display data on oled 1.3 inch screen after 5 seconds but update data on google sheet after every 15 minutes

Question

I am working with DHT22 sensor and NodeMCU to get temperature and humidity values. I want to store values on google sheet and also display values on 1.3 inch oled display. I have used millis() to do multitasking but still not able to do multitask. Both task (display on oled and update on google sheet) take place after 1 minute interval. Please suggest what modifications can be done to code.

#include <Wire.h>
#include <ESP8266WiFi.h>
#include <WiFiClientSecure.h>
#include "DHT.h"
#include <OneWire.h>
#include <SPI.h>
#define DHTTYPE DHT22 // type of the temperature sensor
#include "SH1106Wire.h"
SH1106Wire display (0x3C, D1, D2);

unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 4000;           // interval at which to blink (milliseconds)

const int DHTPin = 14; //--> The pin used for the DHT11 sensor is Pin D1 = GPIO5
DHT dht(DHTPin, DHTTYPE); //--> Initialize DHT sensor, DHT dht(Pin_used, Type_of_DHT_Sensor);
#define ON_Board_LED 2  //--> Defining an On Board LED, used for indicators when the process of       connecting to a wifi router
const char* ssid = "OPPO F11 Pro"; //--> Your wifi name or SSID.
//const char* ssid = "SWE-SEEIT"; 
const char* host = "script.google.com";
const int httpsPort = 443;

WiFiClientSecure client; //--> Create a WiFiClientSecure object.
String GAS_ID = "AKfycbxoDW-7HxrMx90MH7ggsM_0DOTz3gIj-Z06kWTGOwOaoFoaUxW4xfGn_8L7WJh6LX3o"; //--> spreadsheet script ID

void setup() {
dht.begin(); 
delay(500);
display.init();
display.flipScreenVertically();
Serial.begin(115200);
WiFi.begin(ssid, NULL); //--> Connect to your WiFi router

pinMode(ON_Board_LED,OUTPUT); //--> On Board LED port Direction output
digitalWrite(ON_Board_LED, HIGH); //--> Turn off Led On Board

while (WiFi.status() != WL_CONNECTED) {
digitalWrite(ON_Board_LED, LOW);
delay(250);
digitalWrite(ON_Board_LED, HIGH);
delay(250);
}
digitalWrite(ON_Board_LED, HIGH); //--> Turn off the On Board LED when it is connected to the wifi router.

client.setInsecure();
}

void loop() {
int h = dht.readHumidity();
float t = dht.readTemperature();
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t)) {
Serial.println("Failed to read from DHT sensor !");
delay(500);
return;
}
String Temp = "Temperature : " + String(t) + " °C";
String Humi = "Humidity : " + String(h) + " %";
Serial.println(Temp);
Serial.println(Humi);
servosweep();
sendData(t, h);
delay(60000) ;
}

void servosweep(){
int h = dht.readHumidity();
float t = dht.readTemperature();

unsigned long currentMillis = millis();
if (currentMillis - previousMillis >= interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;
display.setFont(ArialMT_Plain_16);
display.clear();
display.setTextAlignment(TEXT_ALIGN_CENTER); 
display.drawString (60,0,"Temperature (°C)");
display.setTextAlignment(TEXT_ALIGN_CENTER); 
display.drawString(60,16,String(t));
display.setTextAlignment(TEXT_ALIGN_CENTER); 
display.drawString(60,32,"Humidity (%)");
display.setTextAlignment(TEXT_ALIGN_CENTER); 
display.drawString(60,48,String(h));
display.display();
}

}

// Subroutine for sending data to Google Sheets
void sendData(float tem, int hum) {
//Serial.println("==========");
//Serial.print("connecting to ");
//Serial.println(host);
if (!client.connect(host, httpsPort)) {
Serial.println("connection failed");
return;
}
//----------------------------------------Processing data and sending data
String string_temperature =  String(tem);
String string_humidity =  String(hum, DEC); 
String url = "/macros/s/" + GAS_ID + "/exec?temperature=" + string_temperature + "&humidity=" +   string_humidity;
client.print(String("GET ") + url + " HTTP/1.1\r\n" +
     "Host: " + host + "\r\n" +
     "User-Agent: BuildFailureDetectorESP8266\r\n" +
     "Connection: close\r\n\r\n");

 //----------------------------------------Checking whether the data was sent successfully or not
while (client.connected()) {
String line = client.readStringUntil('\n');
if (line == "\r") {
  //Serial.println("headers received");
  break;
}
}
String line = client.readStringUntil('\n');
}