Having A baby

Hi everyone I’m about to get you guys all in my business so let’s start here I’m 24 yrs old and I weigh about 300 pounds and my boyfriend of 4 1/2 years is 25 and he’s about 270 pounds now we have been trying to have a baby for about 2-3 yrs now and it’s just not happen and I’m at the point where I want to give up, but I know I shouldn’t so when it comes to ovulation testing idk how or what to look for if I was to take one and my period last for 2 weeks some times a month I have bleeding sometimes in between periods what should I do I really need some help and some advice for you guys please help us