Been there, done that.
Please, check
Registro Civil is the Gov Agency where you will need to go to submit all your paperwork before getting married. They do mention about TYPE OF VISA. A T3 (TOURIST) visa IS NOT VALID for a marriage license.
Quote" Si uno de los dos contrayentes es extranjero y posee visado T3 (Turista), no se podrá efectuar el matrimonio"
Your girlfriend MUST be 18+ if is underage she needs a letter from her parents where they approve the marriage.
Start now getting your documents together and also the following:
All and everything that shows that you have a real relationship with the person that you want to marry as: Pictures, Call logs, Emails, Mails, Gifts that one have sent to another, etc Everything can be use for this.
Get your personal documents together:
-Birth Certificate. (must be stamped from the India Gov Agency that takes care legal docs, translate it if are not in Spanish, get the translation notarized in Ecuador)
-Copy of an ID (full colors) This should be your passport
-Prove of marital status. Are you single? Are you divorce? Are you widow? You MUST prove it.
-Copy of the page where your visa was stamped when you got into Customs in Ecuador.
-Movimiento Migratorio (They asked me for this but the website is not showing this as a doc needed)
-You need to choose 2 witness and get their full color copy of their IDs
You also will need:
Speak Spanish or get a translator with you.
She will need:
-Birth Certificate (Is not show as a requirement in their website, they asked me for this)
-Cedula/Ecuador National ID
-Datos de filiacion (They asked me for this, it shows who are the parents, where they were born, age)
You both will be interview (separate) the day that you submit your documents.
Be sure that you know personal things about one another as:
-How many siblings?
-Father's/Mother's names?
-Where and when they were born?
-How they look like?
-What kind of food do you like?
-What are your favorite colors?
-What kind of music do you like?
As soon you have your marriage license you may want to submit your documents for an AMPARO visa or SPOUSE VISA.
Please check facilitator BEFORE giving them any money. Many of them are scamers. Double and re check before doing anything with them. When they want your money are nice then they turn on you.
Some people had said that some facilitator who has good reviews (in a specific Expat site) must had paid to people to say nice things about her/his service because the reality is different.
Good luck!