Hi and welcome,
From what i understand MS research is still on going in developing clinically useful genetic biomarkers, Genome research and association studies have found more than 300 MS genes, but that doesnt take into account any other influential factor associated with MS....most if not all of the testing available to date doesn't include all known genes into the odds ratio model they use, or consider anything else in their predictions, honestly there are still a lot of unknown factors involved in predicting who will genuinely be diagnosed with MS that you should seriously wonder on their accuracy....if you look you'll find people diagnosed with MS who's genetic testing came back with minimal susceptibility to MS, accuracy at this stage is still questionable.
There isn't anything specifically that you have mentioned symptom wise that is actually suggestive of MS and or couldn't be more likely explained by many other conditions, eg MS doesn't cause all over the body anything, symptoms in all peripheral limbs (both hands and arms, both feet and legs) are more suggestive-consistent with the peripheral nervous system whereas MS is the central nervous system and doesn't typically cause bilateral symptoms in both upper and lower neural tracks...
Heat intolerance in relation to MS is not the same as what most people understand heat intolerance or hypersensitivity to heat to actually be eg a feeling of being overheated when the temperature around you rises, heavy sweating, headache, dizziness, weakness, cramping, nausea, fatigue, night sweats, easy bruising, hot flashes, feeling faint, body aches or pains etc
When someone has MS, even less than 1% increase of their core body temperature can temporarily cause the return of their remitted neurological issues or cause their existing neurological issues to worsen until they have cooled down and rested, symptoms generally resolve when the source of the increased temperature is removed...in MS its called Uhthoff's phenomenon and an increase in heat can be environmental and internal temperature from activity, exercise, infection, shower and bath water temperatures etc
I would recommend you don't worry about MS coming up in the genetic tests you've had, speak to your dr about what your experiencing because it honestly is more likely to be something commonly associated with the symptoms you've mentioned than to be a neurological condition like MS.
Hope that helps....JJ