Why my average buy price is low?

Hi, I noticed that my portfolio buy value was around 128,000 on 6th. And then I made a profitable trade worth around 3000. After this, I bought some securities. In general, I would expect my portfolio buy value should go up by around 3000 (less brokerage). But it is showing 127,000. How is this possible? Also, there is no balance free cash. The present value of the whole portfolio is 122,000, which doesn’t matter. If this is the case, then how can I actually know whether I made any profit?