How my 15000 blurt became 7000 on Robiniaswap ?

On October 1st RobiniaSwap was launched and at that time i took part in the liquidity pool. I took part in three different pools out of which one was blurt-bnb liquidity pool.

I remember i purchased 30000 blurt for $120 approx at that time and equivalent amount of bnb with that.

Then i took half of my investment and put it into rbs-bnb and steem-bnb pairs as well so i was left with only 15000 blurt and equivalent amount of bnb into the blurt-bnb pool.

Today when i withdrawn my liquidity tokens for the same i got back only 6700 blurt and 0.39 BNB.

Source

blurt is almost 10 times from the price i bought it for RobiniaSwap participation and bnb is almost double it's price. So on paper it might look that i have suffered a nice loss but it is not how it looks like.

My investment at that time was somewhere around $300-350. but now i have $480 with of blurt and bnb thought the amount of bnb and blurt are not the same.

I am fine with whatever i have now but can someone tell me why did this happened ? maybe sometime with good knowledge of liquidity pools can tell about that.

Thank you