Sorry Maisie but Rowan is spot on, your dog must come first in this respect, if you cant give it the attention and exercise it needs maybe you should look at re-homing.
Many dogs are not house trained at 3 months, don’t expect too much from him just yet.
Rowan, I agree male dogs will stop and sniff and pee at everything, this should really be stopped in male dogs, its just sent marking and not necessary. Imagine if when a pack of wolves were out hunting and every male pack member done this, they would never get anywhere.
Mine don’t stop and mark, I’m the pack leader and not them, if there is any boundaries to mark, I will be doing the marking not my dogs, So if you see me peeing up a lamppost................... :-)