I would hold off on buying new seats right away. You need to give your rear end some time to adjust to yee old ass hatchet. Contraire to popular belief, a huge cushy saddle will actually be less comfortable than a narrow saddle. This is due to the gel in the lazy-boy saddles flowing and squishing into areas in your...anatomy...that it shouldn't be. Sure they are comfy for a wander down the board walk or around the block, but once you get into the 20 mile range (which won't be long) you'll be wishing you were back on the narrow saddle.
Now that is not to say that all narrow saddles are created equally. If you really want your sit bones measured, find yourself a Specialized dealer and ask if they have an ass-o-meter (seriously), which is a device you sit on to measure your sit bones. The measurements will then be used to find an appropriately sized saddle.
Do you have a pair of cycling shorts yet? These will do wonders to improve your comfort on bike. If you have issues with modesty you can buy mountain bike shorts which have an outer shell over the regular cycling shorts which look like cargo shorts. Or you can wear gym shorts over the cycling shorts. We won’t tell on you.