Hello,
Considering your age, perimenopause is an important possibility for delaying of your periods. Symptoms of premenopause are irritability and mood swings,hot flashes,night sweating,irregular periods,decreased blood loss during periods,dry vagina,breast heaviness and tenderness and joint and muscle pain.
Treatment is by hormone replacement therapy.
I feel that an evaluation by a gynecologist will be helpful.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Honestly it could be either your weight or your age. 4 stone is a lot, is there any medical reason why you gained so much? I would suggest having your thyroid tested to help rule out a thyroid cause for your weight gain. Besides that there are over the counter tests to see if you're starting menopause. I've seen them usually by the ovulation and pregnancy tests but if you ask a pharmacist they should be able to help you find one.