Adora, when you leave St. Petersburg instead of following I-275 over into Tampa and then to Orlando, instead drive SOUTH on I-275 and cross the Sunshine Skyway Bridge. Here is some information about it:
http://en.wikipedia.org/wiki/Sunshine_Skyway_Bridge
Once you cross you'll reach the junction of I-75 which you can then take back north to reach I-4 for the remainder of your journey east to Orlando.
The bridge is an incredible drive and it's unlikely you have anything like it in Newfoundland. The toll is only around $1.50.
BobK/Orlando