Anyone else’s LO not sitting yet?

Is anyone else’s LO not sitting or even tripod sitting yet? My LO is 25 weeks now and has no interest in sitting. I was hoping to start baby led weaning soon but at this rate we’re never going to get there😕

Every time we practice sitting he stiffens up and pushes back or he leans forward and puts his feet in his mouth. I’m starting to get a little discouraged.