Is this right or wroung?

is this right? i usually get my period the end of the month but i havent gotten it till the middle of july today they 18 does tht count as a missed period bc im realyl confused about it it happened lyk this in january 2. i've heard that ur first period b4 ur missed period when u have twins is lyk tht does tht mean im havin twins?! Im puttin on 10 pounds in da last month. &also im havin tuberculous syptoms i hav 5 out of the 8 syptoms have a nasua heartburn intigestion upseat stomach diarehea