Hi SheilaJean and welcome to Cruise Chat.
To be sure, it'll be tight with 4 adult sized people in one cabin on the Sovereign. The rooms on that ship are small, storage space will be at its limit, not to mention that you'll all be sharing one bathroom.
On the positive side, on short cruises like the Sovereign does, you're not spending a lot of time in your room. You're really there just to change clothes and sleep. Depending on how old the boys are, you may be changing for bed long before they come in for the night...
March and April still can be Spring Break time.