Hi Hannie,
You are obviously reluctant to add your tree in WikiTree, and with all your last names I would be as well. Without that, you can't prove direct line to you.
However, if you know who your parents/grandparents are, you could see if they are already here in WT, and search for their connections using the relationship finder. Or you could create them without adding your connection, so long as you have factual data. As suggested before, one you connect to the already existing profiles, then connections begin to show up in the searchs.
For example, your last name Spenser. When you are on any profile page, including your own, you can click on the search button near the last name box filled in with Spenser and see a list of all of them. You will see there are almost 21,000. They are in a weird order, I like to click on the date order, or narrow the search with first name as well.
If you change that entry to any other name, for example Mountbatten, you will see there are many fewer (I think it was 11). But that doesn't seem to be your blood name, so that connection would be found on the connection finder instead of the relationship finder.
Good hunting,
Rick