Praise be to Allaah.
If you were certain that
your menses had ended and you formed the intention to fast before dawn, even
if it was one minute before, then your fast is valid, even if you delayed
doing ghusl.
See the answer to question
no. 37936.
But if you were uncertain
as to whether your period had ended, but you still intended to fast, then
the fast was not valid because of your uncertainty as to whether your menses
had ended.
Shaykh Ibn ‘Uthaymeen (may
Allaah have mercy on him) was asked about a woman who fasted when she was
unsure whether her period was over, then when morning came she saw that it
had indeed ended. Does her fast count even though she was not certain that
her period had ended?
He replied: Her fast does
not count, and she has to make up that day, because the basic principle is
that the menses was still there, and her starting to fast when she was not
certain that her menses was over means that she started to do an act of
worship when she was uncertain as to whether one of the conditions of it
being valid was fulfilled or not, and this means that it does not count. End
quote from Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen
(19/107).
If a woman knows that her
menses has ended, she must do ghusl so that she may pray, and it is not
permissible for her to delay that until the time for prayer ends. If she
does that, then she has to repent, as well as make up the prayers that she
has missed.
If she forgets that her
period has ended – as you mention in your question – then there is no sin on
her in sha Allaah for delaying her prayer, but when she remembers she must
do ghusl and offer the prayers that she has missed – as you did.
We ask Allaah to forgive us
and you.
And Allaah knows best.