Visitor Visa - B2

Morning, i'm italian and I'll got with with my peruvian girlfriend in Peru and our flight has stop on the Miami for only 68 hours. 20 days ago embassy denied her B2 visa INA Section 214 (b) ragion,
I read on this site that letters of support from U.S. family and friends cannot guarantee visa issuance; rather, consular officers consider the travel plans and ties of each applicant to determine if the applicant overcomes the presumption of immigrant intent. We just payd for all flight trips, including perù 3 local flights and hotels, we provided all tour details, she has full job contract from 3 years, and she lives in italy since 2005 with regular permits, but she has not property, has a little bank deposit as she often send money to perù family as all foreign people, only one brother that doesn't live with her; she earns only 800€ for month, will be this one, the problem? we have a friend in miami where we'll stay during our brief USA stop. Someone told me that for visitor visa success, she should show a well paying permanent job, or married with me.. How can we show, that it's not immigrant intent????

we have 68hours of layover (10hours the first day and 58hours of last day of our whole peruvian tour) as you can see on this image
https://docs.google.com/document/d/1oJxSmfKr_z4UO6fMWFh1SJzplk3tEhiQM0DftnNZkF0/edit?pli=1

We have new meeting next week..
please help..

thanks yajaida