As Mr M indicates, we live in a sea of emf radiation as it is and it is having no discernible effect on the general population. Even assuming the wifi - which is not particularly strong afaik - was causing some reaction it would seem to be the exception rather than the rule. For instance, I have lived and worked around wifi for years as do many folks I know and I have experienced nothing nor heard of any unknown health issues as do most people of all ages; at the very least there is no effect apparent that would be more prominent on usual risk groups like the young or aged.
Now in regards to your situation, experience, recording and small test, unfortunately that's individual experience as Mr M puts it, or anecdote as it might be more commonly termed and anecdotes are practically meaningless in this context. There are just too many issues with this kind of evidence for it to be credible scientifically. For instance, memory is fallible, your memory, mine and everyone else - maybe bar those with eidetic recall - and we have no idea what has been recalled and what has not, nor do we know what blanks the mind has subconsciously filled in or embellished particularly in light of later knowledge. I'm not suggesting that you are deliberately misleading - though some folks do exactly that - but that recall is not dependable even if someone is personally certain that they are correct. Then there is the issue of the subjective interpretation all humans have and why science employs controls in experimentation to remove that subjectivity. For example, we have confirmation bias where events that confirm a hypotheses get noticed whilst events that do not go unnoticed and immediately forgotten. There is also bias itself, dissatisfied with the GP's diagnosis you search on-line and encounter certain information that seems to account for what you experience, and from there you may then unwittingly interpret everything through the lens this information has imposed because it has appeared to explain the situation. Btw can I ask where you got the bulk of or what you consider the best information?
The test - at least as described - is not really of significance, one event is not statistically significant and could easily have been an unfortunate coincidence that then fed an already acquired unease over wifi. There is also the possibility that you had in some way become aware of the unit being on and thus unwittingly spoiled the test. Controls exist in experimentation to eliminate any chance of subconscious cues distorting the data. The thing is, we don't know exactly what you knew or came in contact with as we simply cannot see from your perspective. Nor is it likely possible to run a properly controlled experiment in such a setting I might add, thus there could never be any certainty of any result derived. As it is, nothing of use could be drawn from one test.
I don't doubt that your symptoms were real, I just doubt the link you've drawn because there is no credible evidence I'm aware of that would allow for such a link. I accept that you appear to have no issues caused by anything I mentioned but that was fairly limited conjecture. I've no idea if you are stressed and linking a series of stress related issues, minor niggles and the odd other event coloured by information from perhaps non-credible sensational resources - itself increasing that stress and fear - and creating a link where none actually exists.
I have a few very close friends that are GP's and neither knew anything about EMF levels of WIFi sickness.
Now a reason why your GP friends would not know of this wifi sickness is because so far, there is no such thing that I am aware of and they probably are not aware of anything either. It should also be noted that GPs or any form of doctor does not mean infallibility and it could be that your GP has had an oversight in this case; a poor GP is also not beyond the bounds of possibility. Due to there being no known issue between health and wifi and that you have had symptoms of unknown cause, it may be a good idea to seek a second opinion and tests to be sure there are no other issues that may have been missed and are just temporarily dormant / receded. As you say, you found your GP's reaction to your symptoms to be less than you would expect for anything involving odd heart rate, if you can, get a check up and be certain nothing else is responsible.
Hope is but the first step upon the road to disappointment.