Hello Jeanette,

It is indeed a sweet mock orange!  The little white flowers give it away.  A rose of Sharon would have larger flower like that of a hibiscus.

Here is a basic overview of some pruning tips.  Basically there are certain shrubs (including a sweet mock orange) that can get a hard pruning in the spring and others than won't withstand anything extreme.  Typically it's best to prune after it blooms and know that the pruning will likely reduce blooms the next year.

https://www.ksre.k-state.edu/news/stories/2020/10/pruning-trees-shrubs-in-spring.html

This is a resource that gives some details about the plant so you can learn a bit more about it.

https://plants.ces.ncsu.edu/plants/philadelphus-coronarius/

Because it sounds like it has needed more light and now has it, I think I'd suggest letting it grow a bit more this season and then once it's strengthened up a bit, prune it next year.  It looks leggy rather than bushy which is often a sign of not enough light.  You could also find a fertilizer that will give it a gradual release nutrient boost.  A local garden center should carry something.  If you want to find out the nutrient value of your soil, UVM offers a soil test and will talk you through the results.  You'd have information from that if there are any nutrient issues contributing to the plant's growth.

https://www.uvm.edu/extension/agricultural-and-environmental-testing-lab

I hope this helps!

Thanks,