I made a program for my friend, a patient database program using VS 2010. I'm worried if my program messes up she loses all the records.

Here's what I remembered doing. Maybe you guys can identify how I can fix this or you can give ideas on how to avoid the same mistake.
1. I used Visual Studio
2. I made a VB Windows Forms Application
3. I made a Service-Based Database called Database1.mdf which is a Dataset Model
4. I chose save connection string to Database1ConnectionString
5. Dataset name is Database1Dataset
6. I added a table to the database and put stuff in the Columns and data types.
7. I then added it to the Data Source.
8. I then dragged from the Data Source, each column to the forms so they have a Label: Textbox
9. Then dragged again to get a datagrid view.
10. Edited the forms to have better looking add, new, save, previous, next buttons and added a simple search using filter.
11. Then I published it to my computer. After testing, I archived it then sent to my friend.
12. She installed it and is now using it.

She was glad with how simple it was cause I made it with Visual Studio. Now I dunno how to export the database file from her computer/copy of program to make a backup. I dunno what to do.
I know I didn't ask for anything in return but if the program messes up I'd feel bad. 1k+ records already jesus christ and the program has like 74 columns/textboxes. Someone help please.

BTW the DataBindingSource is the thing that connects the textbox to the database.

EDIT:

OMG she says she's just going to add all the records for this year and tells me it could reach 15k or more records total this July. Holy **** I'm just a newbie programmer what the hell did I get myself into. I just copied stuff from youtube so I can make her a program.

Someone please help me with making a new program(if needed). With that amount of records, what database should I use? The important thing is it's easy to use like how I made it with Visual Studio. Or am I panicking too much and 15k records is nothing?

I don't mind re-creating the program.