Hi Karen, welcome and thank you for your question. My name is ***** ***** I am glad to assist you today.
I am very sorry about your issues. Unfortunately, I have checked your gmail account's recovery options and indeed, you only have 1 recovery option and that is a phone ending in 71. It is really unfortunate since you cannot change or update that phone now -- it can only be done when you are LOGGED IN to the account.
Therefore your only best option is to submit the recovery form. Have you submitted the recovery form already? I am referring to the form where you are asked for the date your Gmail was created, last sign in, subjects of your emails, few contacts, etc.Please let me know by replying to me here so that I can help you further.