Awesome! I love questions that I have never heard before. As a result, I'd love to take a "stab" at this one (no pun intended.)
14 degrees Celsius is a little cool, around 58 F. As a rule of thumb, a body that is still warm and not stiff has been dead for not more than three hours.
- Rigor Mortis, by itself, is not that useful in determining time of death. The average time is 5 or 6 hours, but it may start much sooner or later than that. After about 36 hours the signs would disappear. As a best guess, because it is a little chilly (which would delay Rigor Morits) your description of "little rigor mortis" would indicate a death time of 30 minutes to maybe 8 hours?
- Livor Mortis, likewise, is not the best determiner of death time either. It is usually seen from 1/2 hour to 1 hour after death. That would seem to indicate that the body in question was less than an hour old. It would be useful to know what happens when you press the skin...does it stay the same color or lighten? It will lighten up to about 4 hours and reduce until about 6 to 10 hours after death, at which time the color change is permanent.
- The instar larvae is harder, in my limited opinion, to account for because it depends on what kind of insect it is. When you say "first instar larvae" that would seem to imply that it was a very young bug. It is kind of gross, actually.
- The definition of "warm" is also a problem. If you knew the exact temperature of Ms. Stabby, it would be easier to guess TOD as the body cools about 1 degree per hour under normal conditions.
If you put all of these things together, it is my guess that she has been dead less than two hours. That would account for the lack of Rigor Mortis, Livor Mortis, and the fact that she is still warm. It is indeed gross that the bugs would find her that fast, but I'm not sure how much it helps in this case.
Of course, I am not a doctor, so take my opinion for what it is worth! Let me know if you find out the real answer...I'd like to know how off I was!