I can take 2+ years for your period to regulate, the pill can regulate it...taking iron could too and evening primrose can also regualte it...
maybe try using a bit of lubrication when inserting a tampon, you're not supposed to feel it once it's in...you could try using a mirror and work out when it's supposed to go...
if your tampon hurts you have inserted it wrong as you should not feel it at all. periods can be irregular when they first start it is pretty normal. mine were all over the place for ages and then started every month. dont feel self conscious it is a natural thing. dont think there is anything wrong with you and you are not immature for not wearing tampons. when you feel comfortable in them then wear one but dont do it unless you are comfortable.