Is this late Implantation Bleeding, Need some adivce please

So my husand and i are ttc #3. We want to finish our family so i can become a surrogate in the next 2 years. we did our bding during our ovulation time. Ive been feeling horrible for about 4-5days now. I had a huge temp dip at 7dpo, and another dip 10dpo. I have had negative pg test even today. I have been nauseas, dizzy, light headed,all of these combine and it goes so bad i cant even function and have to lay down during the day, im weepy and want to try alot, crampy, back aches, pee alot headaches, and achy down there. Now today 12dpo I started spotting, i got really depressed thinking its my af, but after 5 hrs i took my tampon (sti) out and it was not even half way filled. there was brown, and light red colors, my cramping has pretty much gone away, but still dizzy. Im trying to figure out if I have had a late implanation on 10 dpo and now im experencing the bleeding and cramping from that. And possbile reason for it being late on implanting because i have not had an offical af since my son was born 9 months ago and just weaning bf, and only was ovulating? so there was alot of uterine lining?. Im trying to figure out if this is implanation and maybe get a positive test in a few days?? anyone experence this or have any advice? i know i need it wait it out and see what happens but need some ease on my mind!! please someone