Is a compensatory fast considered valid if the intention was not explicitly made overnight, and merely the intention to have suhoor and fast was sufficient?

The matter of intention (niyyah) is straightforward. Whoever thinks of themselves as fasting tomorrow, at any part of the night, has formed the intention. Based on this, since the thought of fasting crossed your mind and you had suhoor, this is sufficient for forming the intention at night, and your fast is valid, and no make-up fast is required of you. As for obsessive thoughts (waswas), we advise you to disregard them and pay no attention to them, for that is an effective cure for them.