It is less likely that the hives that developed the next morning after peanut ingestion at 11 AM and 3 PM were due to peanut. Almost all allergic reactions which are IgE-mediated will occur within 2 hours of ingestion. Also, hives from foods do not usually last 3 days unless ongoing ingestion occurs. The hives could have been due to the viral infection that led to the ear infection.
The only true test to see if someone is allergic to a food is to do a food challenge, regardless of positive or negative skin or blood tests. People can certainly react with negative skin and immunocap levels, although it is not as common. You may consider having your allergist perform a skin test with peanut butter to see if this is positive. It is possible that after 3 or 4 exposures to peanut your child became sensitized to peanut. The only way to determine this is to do the challenge. However I am unable recommend or not recommend that you do the challenge as I have not seen your child. If you want your child to eat peanuts now, then the food challenge is the only way to determine if she is truly allergic. We do not usually do challenges to peanut until children are much older, 3 or 4 years old, and the recommendation from the American Academy of Pediatrics is to wait until 3 years old to introduce peanut. However it is possible that your child could become allergic to peanut in the future, and there is no guarantee that giving her peanut now would prevent this.
If you do decide to do the challenge, then the safest way to do it is a graded challenge, giving small increasing doses separated by 20 or 30 minutes. Also, about 8 grams of peanut protein should be given over the course of the challenge, as this represents a normal serving of peanut protein.