You began fasting with a sound and firm intention, and you did not reach the level of certainty that your fast was invalidated (because of menses). Rather you were merely uncertain, and your eating and drinking was dependent on verifying that menses had begun. As that did not happen and you completed your fast, your fast is valid and you do not have to do anything.
An-Nawawi (may Allah have mercy on him) said:
If the fasting person is not certain whether his fast has become invalid or not, or he makes it dependent on a certain person entering and the like, the fast is not invalidated according to our view, which is the definitive view of the majority of scholars.
End quote from Rawdat at-Talibin, 1/225.
Shaykh Ibn Baz (may Allah have mercy on him) said:
If he makes his act of worship dependent on a condition – if such and such happens, I will end it – the correct view is that in a situation when one is uncertain about that matter, the act of worship is not rendered invalid, such as if he intends that if something happens to him, he will end the act of worship, or is he is not certain whether some urine or faeces has come out, or he stipulated that if his child came to him for protection, the act of worship is not invalidated. End quote.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said:
A fasting person resolved that if he found water he would drink it. Is his fast rendered invalid?
Answer: his fast is not rendered invalid, because what is disallowed when doing an act of worship does not invalidate that act of worship unless he actually does that action; the intention to do that action does not render the act of worship invalid. This is a useful principle: if someone intends to exit the act of worship, it becomes invalid – except in the case of Hajj and `umrah – but if he intends to do something that is disallowed during an act of worship, it does not become invalidated unless he actually does that thing.
There are several examples of this, one if which is what we have discussed here regarding fasting.
Another example is if he is expecting a phone call and is keen to answer it. So he starts to pray, but intends that if the person he wants to speak to calls him, he will answer, but then that person did not call him. In this case, his prayer is not invalidated.
End quote from Ash-Sharh al-Mumti` `ala Zad al-Mustaqni`, 6/364.
And he (may Allah have mercy on him) said:
If he did not resolve to do that – rather he was uncertain – then there is a difference of opinion among the scholars.
Some of them said that his fast does become invalid, because uncertainty is contrary to resolve.
Some of them said that it does not become invalid, because in principle the intention remains in effect unless he decides to stop it or leave it. This is the more correct view in my opinion, because of its strength.
End quote from Majmu` Fatawa Ibn `Uthaymin, 19/188.
Conclusion: your fast is valid, and you do not have to do anything for having made your intention (to break the fast) conditional, or for having intended to eat if it turned out that you were menstruating.
And Allah knows best.