World not saving

I created a server with a seed called: seed1 and decided to put it on peaceful mode, then i decided mine down to see if the seed description was correct, so as soon as i made a pickaxe i dug down on my spawn point and as soon as i hit diamond and gold i disconnected from my server. So then i decided to reconnect and to my surprise all the things that i built was gone, my mine hole was gone but the minerals in my inventory was still there. So i thought it was just a common glitch so i made the most of it and mined down in the exact same spot to get the diamonds and gold i found again, and did that again and again until i got 64 of each of them minerals and then disconnected. Only then did i realise that the more i did this the more animals there were. Now i can barely move because of how many animals there were and because when i move it has a delay and has a glitchy tine to it. Please help 🙂