An Ashkenazi Rav can give advice to a Sephardi girl and vice versa. If there is a specific question that they can’t answer and feel you need to ask a Sephardi Rav, they will tell you so.
Whenever you ask sheilahs to an Ashkenazi Rav, it may be a good idea to mention that you are Sephardi. But you should first speak to a Rav to find out to what extent you should be following Sephardi minhagim/halachos. I am just thinking that if you mainly date Ashkenazi boys, it may be complicated for you to have to learn everything one way now and then relearn it when you get married. So that may be something to ask a Rav about.