Retainer broke a while ago and I didnt think i needed a replacement, how fucked am I?

Probably 6+ months ago my retainer broke and I didnt think i needed to keep using it anymore, I had been using it nightly for over 5 years at that point and I thought it wasnt a big deal if I stopped using it. Tried to put the retainer on again recently and noticed it isnt fitting anymore, so its almost definite my teeth have shifted (This may have also been because of my wisdom teeth coming in more though).

Realistically, if my teeth have shifted from where they were with the previous retainer just how screwed am I? Purchasing a new one wont be an issue, but im not sure what the process is and what will be required.