Hi, Milly!
Since you describe yourself as "very new," I'd recommend starting with someone a little more modern. Berkhof is thoroughly orthodox, but reading him can be tough sledding at times.
If you can find a copy (currently out of print, I think), I might start with Robert L. Reymond's A New Systematic Theology of the Christian Faith (1998). A feature of his book is that he keys his theological explanations to the Westminster Standards.
Another choice might be Concise Reformed Dogmatics by J. van Genderen and W. H. Velema (2008). It came recommended to me by Ryan McGraw as the best one-volume systematic theology currently out there.
If you'd like something a little more, well, leisurely, I'd recommend Joel R. Beeke and Paul M. Smalley's Reformed Systematic Theology (4 volumes, 2019 - ). The first three volumes are out. Volume 4 might be out late this year or early next year (that's just a guess.) Thoroughly Reformed, easy to read, and very interesting. Don't let its length intimidate you (the four volumes will hover around 5,000 pages by the time they get done) because, as I said, it's not difficult to read - and, it will not only fill your head, it will fill your soul, too.
Just a couple of suggestions.