15 weeks now.....

well so i am now 15 weeks and i feel pretty darn good...appointment is next week on 27th and i am just anxious! to hear that strong heartbeat! i have been cramping way down low...but i know things are growing sooo..i know its normal..we are now in our new place but have not completely moved out of the other...we have not a whole lot of help and husband freaks out with me moving stuff which i know what i can and cannot do..i definately listen to my body when i am tired or dizzy!...so i am wondering when does the 5th month start??? and the 6 month?? i had read 17 months starts the th month but then i was told by a friend its not til 19???
Laurenda