Hello and Welcome to the Chrons!
Well, we have a Workshop section here on Chrons where people set exercises and ideas for each other, so have a look through some recent threads to see if they appeal
Workshop They don't tend to receive feedback, though, if that's what you're looking for.
We also run Writing Challenges -- one which happens monthly requiring a story in no more than 75 words based on a set theme and genre, and a quarterly one requiring a story of no more than 300 words based on an image. You've arrived at the right time as we have one of each starting on 1 April so have a look through recent Challenges to see the kind of work that is produced and whether you might like to join in.
Writing Challenges (It's a bit confusing as there are always three threads for each Challenge -- the main one where the stories are posted, a Discussion thread where we chat about the entries and/or ray guns and pitchforks, and a poll thread for voting at the end of the Challenge.) The stories get some implied feedback by means of votes and mentions at voting time, but there's also an Improving thread for each kind of story, and members can put their work there after voting has finished to get specific critiques.
We also have a Critiques section open for members with at least 30 counted posts.
Critiques To be honest, I'd advise you not to use that even once you qualify on post count, not until you have written your first complete draft, as it can be upsetting to say the least to be on the receiving end of a critique and it's all too possible to be completely discouraged and give up. But do have a look through the threads and see the kinds of comments that are made.
We also have The Toolbox which gives a lot of advice about writing which may be of interest
The Toolbox -- The Important Bits and a thread by Teresa which is very informative
17 Important Things I've Learned About Writing and Publishing
As to mentors, everyone here is happy to give advice and suggestions, but if might be worth trying to find a Writing Group where you can meet -- if only online -- and discuss work with others. We also have a least one member who offers professional writing mentor services if you wanted to go down that one-to-one paying route.
One word of caution, though -- if you're just starting out, don't expect your work to be of great quality from the get-go. I always use the analogy of learning to drive. We've all been driven, we've seen it done, and it looks easy. Then you get in the driving seat... You will do the literary equivalent of stalling the car, clipping the kerb, braking too hard, braking too late, revving the engine and all the rest of it and no matter how good your instructor/mentor, you won't be test-ready until you've got a lot of practice under your belt. So rather than give yourself an artificial deadline of 6 months and a requirement that it has to be eg publishable at the end of that time, just write and learn and enjoy the process, and continue to write and learn, and write and learn, and carry on doing that, whatever the result and however long it takes.