I think getting to another European City such as Frankfurt, Paris, even Munich would give you better chances, then buy confirmed space tickets to Rome. Italy is always challenging, even outside of the summer season. I find April and May are OK, but once you hit June, July and August.... not the best. Try looking at ZED's departing from Canada. There are numerous European departures from Vancouver, Calgary, Edmonton, Toronto, Ottawa and Montreal on KLM, Lufthansa and many others. WestJet is launching its LGW service starting on May 6 so that may be an option for you, then by a confirmed ticket to Italy.