Doing a fasting test today

My Endo has suggested that I do a fasting test to rule out insulinoma, as I have sometimes hypo'd while fasting. She has given me forms to do the blood test if/when my glucoe level drops to 2.7 or below. I have someone who is ready to drive me to the pathology clinic anytime, if need be. The tests she has ordered are for: Glucose, Insulin, c-peptide, cortisol, proinsulin, beta-hydroxybutyrate, sulphonylurea - in the event of low glucose. There is another test form with some extra things on there too: insulin antibodies, FBE, UEC, LFT, TFT, prolactin, ACTH, IGF-1, chromogranin A. I have been fasting since 5 pm yesterday and it's now 9 am and my glucose level is sitting stable at 4.3. The last time I had a hypo while fasting, I got a reading of 2.7 after skipping breakfast one day and then only eating a steak for lunch, then waited about 4 hours while the level slowly dropped.

These are my previous results from 2018:

Pathology Jan 2018 EGFR >90 LFT normal TSH 3.61 mIU/L (0.40-3.50) FT4- 12.1 pmol/L (9-19)
OGTT 75g fasting glucose 4.9, 2-hour glucose 2.1 mmol/L

Medical Imaging Feb 2018
CT abdomen and pelvis No focal pancreatic lesion detected. No acute intracranial, intra-abdominal abnormality detected

March 2018
Pancreatic polypeptide 26.2 pmol/L (<55)
Cortisol 350 nmol/L
ACTH 3.9 pmol/L FSH 1.6 mIU/L
LH 3.1 mIU/L
C-peptide 0.69
Insulin 6 Plasma metanephrines normal: normetanephrine 320 pmol/L (<640), metanephrine 190 pmol/L (<447), 3MT <50 Adrenaline 0.1 nmol/L (<1)
Noradrenaline 1.8 nmol/L (<3.5)
Chromogranin A 40 Sulphonylurea screen negative

I fasted for 27 hours. I was stable at around 4.3 for 24 hours and then I started to go low - slowly. I did the blood tests (checking for insulinoma) at a level of 3.6 which is unfortunate because it's supposed to be done when bgl is lower than 2.8 but the pathology place was closing for the night so I had to do it then. Later the level dropped lower down to 3.3 when the hypo symptoms started. I had some cashews and macadamia nuts and full fat cheese with me so I ate that and then about 15 minutes later I went down to 2.9. I then had a half glass of milk and a strawberry and went quickly back up to 5.3 and now stable (I hope) in the high 4's. Seriously not sure what is going on here but I'm pretty sure this is not normal for normal people or it seems for RH either. I'm feeling very concerned about these results and I guess the next thing to do is a 72 hour in hospital fasting test. Also, at one point the ketone level was at 3.8 which I believe is very high? The endo said if my ketone level gets above 4 that I should increase from 50g to 100g carbs per day.

And yes @Brunneria I have been eating very low carb for quite some time now and I haven't stoppped once. I have a carb tracker app and I'm usually under 40 grams per day and I have been very strict with it with good results in terms of bgl stability and now crashes etc.