Hi Noi,
There are two types of visa, tourist or fiancé.
To get a tourist visa you need to tell them you want to see the U.S. And prove to them you will return home. Don't mention me. The U.S. Looks at everyone as if they want to emigrate here illegally and not come home. You need to prove to them this is not true then get your visa.
Insurance and other expenses we can deal with. I think fiancé visa is premature until you visit here so check into the tourist visa again and speak with some people who have gotten them.
Also, I tried to wire money today and cannot because I need to visit the bank in person and my bank is in NY. Also, wiring is too expensive $75 USD per transaction. So we will need to find another way (other than Western Union) maybe MoneyGram so if you can borrow what you need from your sister now that is the best approach.
Kisses,