ttc with baby #2 need some advice

So my daughter is 7 in a half months and I’m ttc with baby number 2. With my first pregnant I gained a lot of weight and kept that weight. I need some advice on what to do to help get pregnant again. I’m doing everything that I did to try with baby number 1 but it’s not working I try forgetting about trying and just let it happen but it’s not helping at all. I been having lots of intercourse well not as much as I want to since my boyfriend always tired but yeah what are some tips to help with the process.. I was suppose to start my period on august 6th and still haven’t got. It. I did have a period last month but nothing this month. I stopped breastfeeding when my daughters was 4 months and stopped pumping may 8th. on Saturday night I felt nauseous and had a headache and was throwing up and then the next day my headache wasntas bad I tried eating something but immediately I felt nauseous and threw up but then felt fine after I took a nap . every once in awhile I get cramps I took a pregnancy test a couple days ago but it was negative. My body is playing games and sometimes all I wanna do is cry because I want my daughter to have a sibling . Please anyone if you have any advice to give me for ttc with baby #2 that will be great !