@lunalovesjesus BC and a condom is the best combination for safety and not getting pregnant.
4 times a month is definitely more than enough to warrant some kind of protection/ BC.
(Cause even one time is enough, honestly).
Well its not an extreme rule on your moms part, but the bed has to be an excuse XD, but tbh i wouldn't want to hear or be kept awake by people having sex in my own home either, no matter if its the home of the people doing too.
Either way, your mom is smart enough to know that just because it doesn't happen on your bed doesn't mean it doesn't happen, and thats a good thing, she seems to give good advice.