Can anyone help with my problem.. regarding size i think?

ok here's whats up.. me and my gf have been going out for over a year now, about 4 months into the relationship we had , she said it was very painfull but we continued to do it for a couple of months every once and awhile. Now we stopped having about 4 months back, and now when we try she says it hurts soo much that i cant even go in all the way "she says i got thicker".. what should we do?.. im 7.5inch long and 5.75 inch in girth.. is my size the problem? what do you girls think of the problem? thanks.. and no im not a 14 year old kid just puttin up his stats.. this is a seriously problem and i love my girlfriend very much