... I am having serious 2nd thoughts about the field. I have decent board scores ... I am thinking I should have gone for Anesthesia. ...
My biggest concern with this post (and maybe I'm reading too much into it) is that it sounds like you are having your biggest concerns because you had competitive scores and think you could have
gotten anesthesia, not that you actually ever
wanted anesthesia. Neither of the fields you have described are ideal for everyone, so it usually takes doing an elective in both and lots of sitting down with physicians in the field to get a strong sense of which is right for you. You don't say, maybe I'll do psych... but wait, I got good scores on the boards so maybe I'll do gas instead...
Doing away rotations for the more competitive things tends to be the norm so that you get the kind of exposure you need to make this kind of career decision. Hopefully I'm reading your post differently than you meant. But if not, then it doesn't matter what board scores you have, you have to shoot for programs you think, after significant research about the field, that you might like. The people who go into gas want to go into gas, they don't go into it because they can "get" it. If they do, they will be miserable, guaranteed.
As far as the prematch/match/scramble aspect, I agree with the above that you are probably running out of time to extricate yourself from a contract amicably for a prematch, and there is no legal reason the PD must let you out, and you are legally obligated to abide by the contract or owe damages (which probably aren't worth the time of the PD to enforce, since you are likely broke, but if he's a vindictive sort he's got that right to destroy your credit for the rest of your life).
It's probably too late to get interviews for gas, and you'd have to generally interview and line up a prelim as well. You could take your shot at the scramble, but bear in mind that you will need to scramble into both a prelim (not a problem) and an advanced program which will be absurdly competitive and there's a huge chance you will end up after the scramble with no gas and just some one year surgery prelim in a non-geographically desirable area, rather than a categorical prematched psych position; and you will have signed a contract for this one too. I probably would suggest that if you really really really don't want to do psych, that you may want to simply get out of your prematch and skip doing the match/scramble this year and instead spend a year hanging with anesthesiologists and doing research in the field. That would probably give you better odds next year of lining up the gas route without taking whatever prelim/advanced combo might be left over in the scramble if you even get one.
The scramble is bad news. Most people who don't land something in the first few hours go away with something other than what they wanted. So if it's simply a sense of "could I do better" rather than really really can't stand psych or really really want gas, then leave things alone.