Editing a Dataverse table (but not in a form) with variables

[mumcs01]

Who knows. maybe I'm going about this wrong, but my life was really good when it came to sharepoint lists. Then I entered Dataverse and the world got weird. I've created a powerapp that is doing a lot of HR stuff.. (Well for my first real app). One of the things I'm adding is tracking a tech spend budget for employees. This was my entry into Daveverse from sharepoint lists mostly because I wanted to learn about how to use it. And it's really cool. So a sort of experiment. I have a table I created called 'Employee Tech Budget Balances' that has essentially 3 columns (plus all the columns dataverse adds by default). A email (key), balance, and transaction_text. The idea in the power app is to allow a lookup of the balance, and then take a currency input of 'Transaction Amount_DataCard2'.DataField, which is a label on a page - and either add or subtract that from the balance in the dataverse table and repost (patch) the result in the same record in dataverse with the new amount. I have failed at this over the last two days of reading around. Below is what I have. I've tried lots of ways of doing this, but what it comes down to is the fact that I am capable of READING the 'balance' from dataverse using the 'email' as the key. I am incapable of performing an addition from the field (which even if what they put in the field is negative should subtract), and can't get the result to pass back to the dataverse table. I'm using Patch. Below is my most recent attempt whereby when someone goes into this editor it first creates a context variable of the looked-up employee record in 'Employee Tech Budget Balances' and stores it into a context variable named 'stuff'. This seems to work as I can find it in the variables section after running the app.Its after I do this and try to add to it that I don't know how to write back. 

Any guidance would be very helpful. I've accomplished patch functions before with no problem on sharepoint tables. My issue here is that I can't seem to (in programic speak) do it with davaverse.

1. Grab a value from a dataverse table
2. Do math on it
3. Push back the cell or record via a handle. (Similar to what happens in a gallery when you navigate you always have the gallery.selected.X records to deal with... Not sure if this is possible) 

Incidentally, I'm using a field called 'email' as the key in the dataverse table, and Email as the field in the powerapp. Below you will notice that the IF statement is checking to see if there is an email key already in the table (basically this user already exists with a row). If not it's making one. (That works). However, if the email key does exist the point is to take the 'balance' value from that dataverse row associated with that Email, and add it to the 'Transaction Amount_Datacard2' value and store it back to the davaverse table with the updated value. 

If(
IsBlank(
(LookUp(
'Employee Tech Budget Balances',
email = Gallery2.Selected.Email,
email
))
),
Patch(
'Employee Tech Budget Balances',
Defaults('Employee Tech Budget Balances'),
{
email: Text(Gallery2.Selected.Email),
Balance: Value('Transaction Amount_DataCard2'.DataField)
}
),
Stuff.Balance = Stuff.Balance + Value('Transaction Amount_DataCard2'.DataField);
Patch('Employee Tech Budget Balances', Stuff, { Balance: Stuff.Balance } )

);

Set(
_popup,
false
)