No, the Swedish language uses the same tense for what in English would be Past and Past Continuous. It's called preteritum (or sometimes imperfekt).
"I was waiting" would simply be Jag väntade in Swedish. And so would "I waited".
The construct Jag höll på att <verb in dictionary form> is rather used to emphasise what you were actively doing in a certain moment. Or it can be used similar to "I was about to...". Note that it uses dictionary form. So your example should be Jag höll på att vänta, but even though that would be grammatically correct it still sounds wierd. Probably because waiting is not something you actively do, it's more of a passive action, if that makes sense.