Hi and welcome to the BW website.
Can you post what your current day looks like including the short naps, E times, A times and S times (how long) so that we can have a look at it and perhaps try and tweak your routine.
15-20 mins is way too short, your lo does need to nap during the day, to prevent him from getting over tired.
Sounds like he is doing fantastically at night, although if he constantly has those short naps, he overtiredness could catch up with him and start affecting his night time sleep and causing night wakings.