Age gap

My boyfriend is turning 20 in December and I'm turning 17 in August, is 3 years too much of an age gap? Both our parents are okay with it.. But our friends think it's weird, i don't know what to think, we've been together for about 7-8 months and I've always felt like we're being judged, i try not to let it bother me.. Any advice for ignoring it?