# Consumption rate on a small dataset with variability

I am looking to find the consumption rate, or how fast I am consuming energy so that I can later predict when my energy will reach a certain threshold. My dataset is fairly small and looking to see what the best method is to use:

Data

date    Energy_used
4/1/2021    877
5/1/2021    898
6/1/2021    940
7/1/2021    962
8/1/2021    950
9/1/2021    999
10/1/2021   1008
11/1/2021   1136
12/1/2021   1108
1/1/2022    1213
2/1/2022    1222
3/1/2022    1175
4/1/2022    1108
5/1/2022    1144
6/1/2022    1182
7/1/2022    1149
8/1/2022    1124


Doing

We know we can discover how fast we are by using a formula that takes the:

(start - end)/ # of months


For example if we look over a 3 month period, we see (877 - 940)/3(months) = -21 (From April to June 2021) From this calculation we are burning through 21 units of energy per month. However, how would I compensate for the variability within this dataset. The energy fluctuates and is not always constant. What is the best methodology to determine how fast I am burning through this energy usage?

Any suggestion is appreciated