i Need Help Abt A Question ? Dont Judge Please .

So me and my fiance are trying to have another baby after i just had one and she is now 2months old . i got my first period Jan 2nd-6th and i breastfed for 2 1/2 weeks my period use to be regular but now im insire cause its only been 1 period since i gave birth . we have had sex atleast 3-4 days every week till now i feel nauseas and tired alot and i also get cramps and headaches ive taken atleast 2 tests every week and they are all negatives but i also dk if ive ovulated aince i just gave birth 2mnths ago so my question is how early can i get a blood test dons for it to be accurate ? or should i wait to see if i get a period next month since im unsure if its a regular AF or irregular . but im eager to get a blood test done . HELP!