Deepthroating!

So I just started having sex with this guy who is very experienced and I'm not so much. I've only had sex with one other person before him and the difference is crazy! With my ex I would give him head and he would go crazy and I could deep throat like nothing. But now one of the big differences with this guy is clearly his dick is bigger, which is AMAZING! But I can't deep throat!!!! I try and I almost get it but then I gag! It's so frustrating! He's very cool about it and tells me I'm getting better but I don't like not driving him crazy about it! I need some tips to be able to deep throat better. Any ideas?