GSM Shield 2 - Power down and power up

Hello guys!

I'm new in arduino programming jurney. I made a project including an arduino uno, an arduino shield gsm 2, and some others sensors (temperature and humidity). I also bought one battery 12 Volt with 7,2 Ah. Project:

  • When I power it up for the first time
  • Collect data
  • Send SMS to my phone number
  • Delay for 24hrs
    And does this all time.
    Battery last 3-4 days max.
    I used Low.Power library but it didn't last longer. (Any way to make battery consumption less ?)

I have also this question: The place which I am using the project doesn't have too much signal on the area and sometimes signal is missing or lacking when devise has to send me SMS and finally doesn't send me SMS. Is there any way to be sure when signal come back to send SMS?

Thanks in advance for your help!