Calculate rolling average and use for missing values - powerbi

Question

I am trying to build a model in PowerBI that forecasts future values based certain inputs. The issue I am running into is that some of my data is missing rows, and I also need to use the last value of data as the one for the next period, to which I will add additional (calculated) values. I used an index that starts at -5 and goes through 30, and added a date column expressed as Today()+Index. The data looks like this:
Index | Date Index | Values |
------------------------------
-6 11/4 2
-5 11/5 5
-4 11/6 7
-3 11/7
-2 11/8 5
-1 11/9 4
0 11/10 <-- This is today
1 11/11
2 11/12
...
What I need the data to look like is this:
Index | Date Index | Values |
------------------------------
-6 11/4 2
-5 11/5 5
-4 11/6 7
-3 11/7 4.667
-2 11/8 5
-1 11/9 4
0 11/10 4 <-- This is today
1 11/11 4
2 11/12 4
...
The Dax Formula I have is:
Values =
If(
AND(
SUMX(
Filter(
Table 2,Table 2[Date]='Summary Table'[Date Index]
),
Table 2[Initial Values]
)=0,
'Summary Table'[Date Index]<Today()
),
Calculate(
Averagex(
Table 2,Table 2[Initial Values]
),
DATESINPERIOD(
Table 2[Date],Today()-1,5,DAY
)
),
SUMX(
Filter(
Table 2,Table 2[Date]='Summary Table'[Date Index]
),
Table 2[Initial Values]
)
)
Note that I am pulling in my values from a different table, Table 2, which has multiple dates with values, which I am summing in this summary table by date. For some reason, the formula is filling in an incorrect average value for missing values, and not pulling the last value (from Today()-1) through to the end of the data. Any help or advice would be appreciated!