What size diaper is ur LO in ? Not sure I have the right fit

Jess • pround momvof two beautiful boys
My son is 7 weeks between 10-11lbs .. I have him in size 1.. it's very baggy around his private area but snug everywhere else. He once in awhile pees out the top around belly button. He will usually leak out the side if he's laying on his side. Thoughts??