Basic Question on Binance Futures

Opened a long position on ETHUSDT when ETH was 2.453 USDT. Put something around 500 USDT and adjusted the leverage as 7x. Then in time ETH started to rise, I first adjusted the margin and added 500 USDT more and adjusted the leverage as 20x. Then put more and ended up with 2.168 USDT margin and adjusted the leverage for the last time as 25x. At the very beginning I was expecting something like this: ETH rose like say 5% and my leverage was 7x and it makes 35% and my Unrealised PNL should be 500 USDT*0,35=175 USDT. But it never happened that way and in the end I now have some positive PNL which is way smaller than I was expecting. It is obvious I'm missing or didn't understand some point. Can someone basically tell me how the system works? Thank you.