Brute force a DMG file (256-AES)

In short: you know that moment when you want to encrypt your file, but want it to be totally safe and secure, and you come up with a total new, long and above all random password. Well I do the same for most of my stuff, until lastly: I was under huge time pressure and wanted everything to be secure, so I made a DMG-file on my MacBook and secured it. Several weeks later, when I wanted to re-use my file I noticed that my first attempt was without any success. So I thought of a typo and re-entered. Again, no success. Again, thinking no bad: I re-entered the password slowly and securely. Again, no success. Until after some point and trying to come up with other combinations of what I thought was my password, I realized: I had never used this password before and had lost it. Of course, in such a case, one refers to Google. However, with my basic knowledge in encrypting I knew: decrypting a 256-AES password is nearly impossible. At least not without knowing key elements of the password, some kind of supercomputer and a lot of knowledge of decryption (or at least Linux for JTR). So becoming desperate, I tried several solutions, since these files were important for me and I had to get back in. All without success, until a friend of mine referred me to this website. This is one of my last solutions. I have not used JTR, because I didn't make it through the installment procedure, with the terminals and directories, it didn't make much sense to me. I am hoping that someone is able to brute force this password, but it contains sensitive information. So before starting the procedure I will need to ensure a way to do this properly and not losing all the sensitive information. I have read a lot about this topic and know by now it is pretty hard to do this job, but I'm not waiting around for people to tell me that again. Any valuable input however, is appreciated!