My cycles are still regular, but I have

Yes — perimenopause symptoms can show up while your periods are still regular. Regular cycles do not rule it out, and the pattern you describe (night sweats plus brain fog, with cycles still present) is one clinicians commonly see. What I can't do from here is name the cause: night sweats and foggy thinking have several possible causes besides hormone change, including thyroid and anaemia problems and plain sleep debt, and only an examination plus their own tests can sort that out. So this is a "get seen, and use the wait well" answer, not a diagnosis and not a treatment plan.

Book the Wednesday appointment and treat the diary as the thing that makes that appointment count — one snapshot of symptoms, not one snapshot of a hormone number.

1) What you already tried vs what works better

Tried: one hormone blood test, read as the answer.

Better, in this order:

• The diary as evidence, not as a diagnosis. Keep it to four things a clinician can act on: the nights that were drenched vs damp, your period start dates and how the flow changed, the nights sleep broke, and any day-time flush or racing heartbeat. Dates matter more than feelings — a clinician reading a dated pattern is reading evidence.
• Keep Wednesday. Bring the diary, your current medicines and supplements list, and the one question you most want answered. If you can, write the question before the appointment so the tired version of you doesn't leave without it.
• The overnight comfort routine, tonight (about 10 minutes). Layered cotton bedding and a spare set of nightwear within reach, a cool or ventilated room, and a glass of water by the bed. This is comfort while you wait for the door — it is not a treatment for anything.
• Say it in one line at the appointment: "Cycles are still regular, but I've had night sweats and brain fog. I want to know what's causing them and what my options are."

Two things worth knowing, both from the NHS page on menopause and perimenopause symptoms (checked 14 October 2026): symptoms can happen while you still have periods, and it is possible to get pregnant during perimenopause — so contraception still matters (for 1 year after your final period if you're 50 or over, for 2 years if you're 40–49).

2) Avoid list — the constraints you set, and the ones I would add

• No diagnosis from this chat, no starting, stopping or changing any medicine or hormone — that is the clinician's call.
• No "mystery powders", no black-cohosh-type or "natural hormone" products bought online, no prescription hormones bought privately. The interactions and the unverified contents are not worth it when you have a real appointment coming.
• Nothing prescribed for anyone else in the house, including anything for the kid or the elder — you don't dose them, and you don't borrow.
• Don't let the diary become a 20-minute nightly project. Thirty seconds is enough: date, sweat level, sleep broken?, period started?
• Don't spend your few spare minutes researching symptoms online tonight. One good page beats ten forum threads.
• Caregiver lever that actually pays: pick the one Wednesday task you can hand to someone else — one school pickup, one errand — and say plainly that you need it covered. Tired caregivers get more from a named task moved than from encouragement.

3) Red flags — when to stop the home routine and get help

Stop and get medical help the same day (or sooner if it comes with the first line):

• Bleeding much heavier than before, or a bleeding pattern that's clearly changed, or any bleeding 12 months after your final period. The NHS page flags postmenopausal bleeding as usually not serious but a possible sign of cancer — easy to treat when found early. Don't wait for Wednesday.
• A racing or noticeable heartbeat with the flushes. The NHS page lists palpitations as a reason to contact your GP rather than wait.
• Fever, weight loss you did not intend, or night sweats that are soaking and persistent — the pattern that needs an examination and blood tests, not a routine.

Call your local emergency number now, or go to the emergency department, for any of these:

• New confusion, drifting in and out, being hard to wake, or anything that is not you.
• Chest pain or pressure, or sudden breathlessness.
• Sudden weakness, numbness, drooping face, slurred speech, or vision going — note the time it started and say it first.
• Thoughts of ending your life or a plan — stay with someone and get help by phone rather than waiting.

Decision tree — screenshot this

1. Any chest pain / stroke signs / new confusion / cannot wake / cannot breathe → local emergency number now. Nothing else first.
2. Heavier or changed bleeding, or palpitations, or drenching persistent sweats with fever or weight loss → same-day medical call, do not wait for Wednesday.
3. Otherwise → Wednesday appointment, diary in hand, and the 10-minute overnight comfort routine until then.
4. After the appointment → whatever they prescribe or advise, plus the diary format you already have.

What success looks like in the next 24 hours — no promises of a cure

• Wednesday's appointment is booked and confirmed, and the diary has real dates in it.
• You know your three red-flag lines by heart, so you don't have to decide at 2 a.m. whether something counts.
• One night with fewer wake-ups from the sweat — plausible, not promised, and comfort-level only.
• One caregiver task handed to someone else.

One question that changes what I tell you next: are the night sweats heavy enough that you change your nightwear or bedding, or just damp?

A clinician appointment is the door here, and I could not verify a specific local clinic or phone number for you this turn — so when you book, use your own usual primary-care route or women's health clinic.