To think I could have ME?

Not advice but I could have written this OP.

Could be, but probably worth getting your thyroid and parathyroid hormones checked too.

www.investinme.org/Documents/Guidelines/Myalgic%20Encephalomyelitis%20International%20Consensus%20Primer%20-2012-11-26.pdf

www.mumsnet.com/Talk/general_health/2618526-CFS-ME-Fibro-spoony-support-thread-2

b12 checked?

Have you had a full range of blood tests done to rule out things like underactive thyroid or anemia? Also get blood tests for things like a vitamin D defiicieny as this can cause exhaustion.
If all of those are clear then have a look at things like your diet and whether you're drinking enough and getting good quality sleep (check out sleep apnoea online. Seemingly healthy people can get it and be totally unaware and it can cause very broken sleep). Are you depressed at all? And do you have regular periods?
If all the above seems fine then it does definitely sound like ME could be a strong possibility. What age are you and has it been going on a long time?

^This is a summary of a CFIDS disability scale from The Doctor's Guide to Chronic Fatigue Syndrome by David S. Bell, MD, published by Addison-Wesley, ISBN 0-201-40797-2. Dr. Bell treated people with ME/CFS for many years.

100: Patient has no symptoms at rest, no symptoms with exercise; has normal overall activity; is able to work full-time without difficulty.

90: Patient has no symptoms at rest, has mild symptoms with activity; has a normal overall activity level. The patient is able to work full-time without difficulty.

80: Patient has mild symptoms at rest, symptoms worsened by exertion. Patient has minimal activity restriction noted for exertion activities only; patient is able to work full-time with difficulty in jobs which require exertion.

70: Patient has mild symptoms at rest. Patient clearly notes some daily activity limitation. Overall, the patient functions close
to 90% of expected, except for activities requiring exertion. Ability to work full-time with difficulty.

60: Patient has mild to moderate symptoms at rest, with daily activity limitation clearly noted. Overall functions 70-90%. Patient is unable to work full-time in jobs which require physical labor, but has the ability to work full-time in light activity if hours are flexible.

50: Patient has moderate symptoms at rest, and moderate to severe symptoms with exercise or activity. An overall activity level is 70% of expected. Patient is unable to perform strenuous duties, but can perform light duty, or desk-work 4-5 hours per day, requires rest periods.

40: Patient has moderate symptoms at rest, and moderate to severe symptoms with exercise activity. The patient has an overall activity level of 50-70% of expected. Patient is not confined to house; is unable to perform strenuous duties, but can perform light duty/desk work 3-4 hours/day, but requires rest periods.

30: Patient has moderate to severe symptoms at rest, and severe symptoms with any exercise. Patient has an overall activity level reduced to 50% of expected; is usually confined to house. Patient is unable to perform any strenuous tasks; is able to perform 2-3 hours of desk work per day, but requires rest periods.

20: Patient has moderate to severe symptoms at rest; is unable to perform strenuous activity. Overall, activity levels are 30-50% of expected. Patient is unable to leave house except rarely, is confined to bed most of the day, is unable to concentrate for more than 1 hour/day.

10: Patient has severe symptoms at rest, is bedridden the majority of the time. Patient has no travel outside of house. Patient
has marked cognitive symptoms preventing concentration.

0: Patient has severe symptoms on a continuous basis, is bedridden constantly, and is unable to care for him/her self. ^

I felt very similar a few years ago. I had issues with my thyroid, but they were resolved. I had numerous blood tests, and was just in the process of being referred for Chronic Fatigue, when I heard about Vit D deficiency.

Although my levels were "low end of normal" I took a supplement, and it was as though someone had plugged me back in.

If I take a daily supplement, stay off gluten (a separate issue for me), exercise regularly, and get enough sleep, then I am fine.

Hope you get it sorted.

I'm ferritin deficient anaemic but have always been so and never struggled like this

Are you taking enough ferritin? I was pretty much deplete of any iron reserves a few years ago, sleeping 9-10 hours every night and having to nap after tea. All improved when i upped ferritin.

Im exactly like this. All day every day. Have had so many bloods done. All come back clear. I thought fibromyalgia maybe ? I have purchased Magnesium and Sunflower oil. Not sure if it will help. But I need to do something as I have 4 dc and can't stop for a minute.