This must be one of those things that seems like a massive deal when you are fifteen. With experience you will just see that it isn't a great issue.
I regularly sit around the office, walk around the building shops etc with my helmet on, with the usual cries of "you've forgotten your bike", "the ceiling inst going to fall on you head" and so on.
I just find that the easiest place to carry it is on my head.
It is all character building, ignore them, they are looking for a response, be it verbal, physical or more subtle shrinking away if they get this response then they will keep doing it. Perhaps refer to it as a lid, or something of a more funky name than a lid (Don't name it Bernard or something)
Carry on as you planned, let them carry on making a fool out of it.
Finally assume everything people shout at you is encouragement...
This week several people have been so impressed by my cycling that I think they was inviting me on a "hunt", but the trouble is they seem to think I am called Richard Head and keep calling out my name as i pass...
Is Ricky Head a famous cyclist?
If that doesnt do it for you assume they are encouraging you like Eddie from American Flyers
View: https://www.youtube.com/watch?v=p8uP-dxllKQ
Just dont lose your shoe. There is probably some irony in that neither cyclist on the clip is wearing a lid.
As an aside, haven't helmets come a long way in appearance in the last 20 years.
Keep cycling, keep fit, get fit/fitter/ enter a few events and they'll soon shut up when the girls take notice! - Remember most events require helmet use.