I have all of my Fields set up in the general Fields configuration. They are all published and are of a variety of types. BUT, not all of the fields are listed in the 'Fields' list for my events.
More info:
>> Running Joomla 1.5.25 and DT Register 2.7.13. (My DT Register upgrade path has been 2.7.7 >> 2.7.9 >> 2.7.13)
>> Some recently added fields show now and some don't.
>> Some old fields show and some don't. Though, every old field I haven't edited recently does show.
>> All events show the same, incorrect, list of available fields.
This would be due to some of your fields being conditional. This is explained in video tutorials. Conditional fields do NOT (on purpose) show in the list of fields within the event setup. When the parent field is enabled for the event, the conditional fields are automatically enabled and will then function according to the default settings given to those fields.