Hi, I completely understand. 12 weeks is still so early - your body has taken 9 months to grow a baby. Everything has shifted, hormones are up and down, it's a massive life adjustment.
I am 7 months pp and my body often feels broken. I have a prolapse, which I started to feel at 2 weeks pp. The GP fobbed me off and told me there's nothing wrong, so I went back and she reluctantly referred me to a pelvic floor physio, who diagnosed me with a grade 1 prolapse. So my advice is definitely make an appointment to get checked out - and push for a referral if you know you're not feeling right.
My prolapse symptoms have improved at 7 months pp but I still feel it at certain points of the month. My specialist recommended these pelvic floor support shorts which help hold everything up. They do help: https://www.win-health.com/evb-sport-pelvic-support-shorts
Re your stitches - you need to go back and get this looked at asap. I know it feels all too overwhelming with all the appointments, baby vaccinations, information etc. You're doing really well, but this is important.
Everything will feel strange with your body. For me, the last thing I wanted to do was be physical with my partner - I had just pushed a baby out! It's so understandable. Have you spoken to your partner about how you feel? Maybe just focus on getting lots of hugs , massages from them, to make you feel special and loved.
While I got back to pre-pregnancy weight quickly, I still struggle with body image as my hips and ribcage are wider. My stomach is also less firm. I focused on buying myself some new clothes that I feel comfortable in, and try to get out every day for a walk.
If you're breastfeeding, that can also be draining on the body. It can give you a back ache, so try using a support pillow if you're not already
Things have improved for me slowly but it's a journey. I completely understand.
There's an app called Peanut, which connects you with local mums. I've met one lady on there who I would now consider a friend. Local baby groups are also helpful and a great support. You're not alone 