How often do you kiss in your relationship?

Something plays on my mind about my boyfriend and I wish it wouldn't but...I know he's not a very public display of affection kind of guy. It does get to me sometimes when we're out and I see other couples all over eachother but ultimately in public, I can understand that some people just don't see it as appripriate and find it awkward. However, he is quite affectionate in private - gives me lots of pecks and very huggy and whenever we watch tv or a film, we're always snuggled up. But for a long time, we don't really kiss "properly" with tongues unless we're having or it's leading up to . I have to be very careful with what I say as he gets sensitive about stuff so I tried to bring it up jokey once and said kissing's not just a ual thing you know and he said he knew but in reality the only time he would do that would be if we were in . I do try sometimes to kiss him properly but he never goes to do it to me and don't feel the same enthusiasm from him back. Sometimes if I do that he sorta does it back but not for very long and sometimes I can't really make it happen as it takes 2 you know and he doesn't do it back! I know everyone's going to tell me that these things go after a while with someone but for me, proper kisses are important because they imply they find you attractive etc. I don't know how normal it is for this to be the case in relationships? How often do you have proper kisses in yours? And I know it sounds bizaare but is there anything I can do to encourage it?