Hello,
Something that doesn't sink in is the tenses you use in a sentence that begins with "ever since".
Here are two real-life examples:
Ever since I left school, I've smoked
and:
Ever since I got a Mac, I have spare time
Why is "have smoked" used in the first example, while the simple present is used in the second example?
The grammatically correct usage is "Ever since I [verb in simple past], I [verb in present perfect]." So for those examples, the first one is correct, but the second one should be "Ever since I got a Mac, I've had spare time."
However, like many grammar rules in English, this one is often ignored, especially when the main verb is "to be" or "to have," as is the case with your second example. So take the "official grammar rule" with a grain of salt ;)
Oh, and thanks for using that expression -- to sink in -- I added it to the list of expressions to use in the lessons :)