My mom trusted me a lot at 10 and now doesn't trust me at all?

when i was 10 my mom thought i was really responsible and gave me all this responsibility and now that i'm older, she won't let me do anything. like, for example, what i've been wanting for a while now, i used to hae a guinea pif when i was ten and i had to take care of it and stuff but i did not and i forgot to give it a chew toy and it's teeth got too long and was not able to eat and died. I really liked that little guy and now i'm interested in a holland buny because it reminded me of the goo times i had that guy and it reminds me of what i did wrong with him and yeah... i'm alot more responsible and my mom doesn't realise that, how do i gain back my ummm "respnsibility" sorry about spelling i'm really distracted