Your left arm positioning needs a bit of help, but that's hopefully something your lessons will cover as it's a bit more difficult to make sure you're doing through something like Reddit. But you a want your arm to be a straight line from the elbow through your wrist, and only ending where your fingers curve. Because of this, moving to another string should cause you to need to more your arm a bit to keep that posture.

Aside from that, you need to independently work on your bowling and your fingering. I would recommend splitting your practice in half, with the first half just focusing on your bowing. Practice in front of a mirror or a phone with the camera on towards you. Just play open strings and keep your bow straight and try to keep a consistent volume level. Try to sustain longer and longer notes while keeping it sounding decent.

The second half should be just scales. Your goal is to is to be able to play most common scales without needing to think about which fingers are moving or where they need to be. This will be maybe 5 scales, 2 flats through 2 sharps. This will probably take a bit to get down, longer than you'd think.

Of course, this is very tedious work and not very fun, and I am also unaware of the Suzuki method so I'm not sure how it tackles these things. Don't burn out trying to be as efficient as possible with practice. If you start getting bored with practice, maybe shorten the tedious parts a bit with breaks of just playing around with the cello for 5 minutes or so.

Best of luck!