Sex and getting pregnant!

So, girls questions! I have been having sex with my fiance for about 5 mnths now...n nothing. Sure, I wasn't like getting my period every month like it's supposed to come but I was really irregular n now that I've been having sex...well um it's been coming since July not always like on the same day but every month. So how long did it take y'all women to become pregnant if your irregular n then become regular? Is there a certain time frame? Or should I just wait n just let it happen if it happens? Thanks gals! Please give me some guidance n support were really wanting that family! Me, fiance and his took kids th st was taken away from him in February. So please need some baby dust sent my way! Sorry for the long information