Home made jam consistency and taste
I think that may be unavoidable.  

Even if (as @Chris H is hinting with his question) your fruit is coming from the same place every time, even if its the same farm, your raw fruit is unlikely to have the exact same taste and sugar content every time.  That will always lead to differences in taste.  

Sweeter fruit will need less sugar, but if you're always adding the same amount then some batches will come out sweeter than others.  

Differences in the taste of the raw fruit are likely, as you're purchasing at different times of the year.  Even just a couple of weeks can affect the taste of fruit significantly-- compare early season berries to mid- or late season ones, for instance.  

In my experience those differences only be come more pronounced with cooking, especially when its done in small batches.  Mass-produced jams have consistent taste by using large quantities of fruit, so the differences between each individual farm's fruits become smoothed and averaged out.  

In my opinion the difference in each batch of homemade is part of the charm, but if consistency is really what you're after I would suggest making slightly larger batches and combining the fruit from several different sources.