I admire the bravery you are displaying in talking about these fantasies, urges, and preferences. What is most important about your thinking is that you are questioning yourself. I think you are asking a good question by reflecting on your preferences.
You are right in noting that ephebophilia defines the primary sexual interest of mid to late adolescents—roughly 15 to 19, but from your description, this may not be your primary age-range preference. The presence of some level of sexual attraction doesn’t qualify as ephebophilia.
Sexologists will often use specific terms for age group preference. Since you’ve identified yourself in your profile as a 20-year-old and you are primarily attracted to people your age this would technically qualify you as someone primarily attracted to adults, or what sexologist would call teleiophilia. If the attraction were to a younger, prepubescent children younger the term hebephilia would be used.
Although these types of urges and fantasies are often referred to as paraphilia, or a sexual fetish, sexologists do not agree on the nature, range, or diversity of unusual sexual interests and paraphilias. But there are two things that most would agree on.
The first has to do with the age of consent, which differs in different localities, as being a clear dividing line between urges and action. Your sensitivity to the idea that acting on some of these urges would be wrong is important to maintain. Consent given by someone not of age would not be valid.
Secondly, it would be the distress or interpersonal difficulties caused by having these thoughts that would be important for you to seek counseling. If they interfered with your relationships with others, or caused undo distress you may want to talk with a professional about it. If this is the case the find help tab at the top of the page can help you find someone in your area.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral