I use a entity field to store points rather than account balance.
Did you not say you don’t want negative?
From my understanding of what you have said and kendash has replied, you want to use account balance for points.
In theory negative or positive is erelivent so ling as your add and use transactions are inverse of each other. However if you want to count points positively you need to reverse the two transaction types/directions.
Currently you have you add points transaction back to front and are using the use points type so it’s going to negative and that in theory would mean your use points (which should be add) will increase the balance back towards 0.
If you reverse the two actions for creating transactions you will go the other way, add will make positive and ue with reduce back to 0.