I have a time series. I plotted it and saw that it is not stationary. Thus, I have calculated the difference. Then I plotted the autocorrelation and partial autocorrelation on the differences, along with the confidence bands. Non of the lags were out of the confidence bands, and the correlations for all lags are very low. I wanted to ask, does this mean that I cannot make good forecasts, or is there something else I could do. What should be the next stage? I would add and say that my series has no trend or seasonality (there is a trend down which at some point becomes a trend up, like a stock graph).