in young and confusedd; kinda worried also

heyy so im a little worried because my whole life that i have had my pierod i have always had is unregular (im thinkin it was because i usedto smoke) because when i decided to stop smokin i had a regular pierod for about 2 months always around the 11 or the 15...i had sex (protected) but the condom wasnt the right size the condom stayed on the whole time but now i skipped a month of my period and on thursday it will be another missed month...so idk is it that im preg. even tho we had a condom or is it just my period skippin like always..beause when i had a irregular period i would skip months every now and then. so im worried i still havent took a preg test. the first week after my missed period i was feelin like i had to throww up and now i get light headed every now and then and i get bad cramps on my lower stomach pains as if they were period pains except i just dont get my perios..and i had no spottin nothin just painn. so what should i do. or is there anyone that can help.? plz and thanxx