How to refine future projections?

So I have this card that is supposed to provide projections of wins from opportunities for the next couple of months. This was essentially calculated by creating a beast mode calculation called 'Win Probabiliy' that took the count total of all wins divided by the count total of all opportunities. This gave me some decimal value that was later summed up, split by month and provided a projection of the wins for the following month. It's not as accurate as I would like so is there a way to refine it or is there a different method I can try? I tried to use the Prediction node in the data science section but it didn't seem to be able to help in my instance since I'm taking the sum of the probabilities when visualizing it. Sorry if this is vague, I'm not sure how to really describe the situation any better. Thanks!