Forecasting using Python
If you use any forecasting model, then it will do over fitting on your data set, as you have just 19 observations. At least 1000 observations are the good point to start applying any machine learning model.

I need to predict Response Rate, % Promoters, % Detractors and %
Neutrals all of which are numeric variables.

You can do data exploration where you start using bar charts, line charts, and try to find the pattern for each of those variables. Using this, if not accurate, but you would be able to understand lump sum forecasted value for upcoming months.
Even built in functions are there in excel. Check this out: https://www.excel-easy.com/examples/forecast.html