With the 't' at the end, 'sammanlagt' is an adverb rather than an adjective here, right?
The use of the present tense sounds kind of weird in English here, at least without some kind of adverb such as "usually" involved.
A more exact translation would be "all added together" or "total." It specifically involves things being added together to create a larger whole. I reposted this as a reply because I realized that you wouldn't get a notification otherwise :)
I wrote "In total, I work three weeks". It sounds similar enough to me, but I'm not sure how correct it really is?