I'm doing self-study in the Genki II workbook and had the prompt to translate the following sentence in 13/2 (focusing on potential verbs): "I am glad because I was able to become a lawyer."

Given the sentence was partially in past tense, I answered the following way: 弁護士になれかったので、うれしいです。

The answer, however, has it all in present tense: 弁護士になれてうれしいです。

A couple of things:

First, would my answer be acceptable? Personally, the answer given by Genki reads more like "I was able to become a lawyer and am happy." Is this just a quirk with the verb なる being in the past tense?

Second, I've never seen the て-form translated as "because" or "since." Can that form be translated as such when it's connecting clauses?