Your baby is starting to make small movements, and can wiggle their fingers and toes. Their stomach and digestive system started forming in week 7, and grew so fast it protruded into the umbilical cord space. By this time, the baby's growth is catching up, and their digestive system will soon go back into the abdominal cavity, which will then close up for good. Baby is also starting to grow fingernails and toenails.
Most of the big organ development is actually finished at this point (that is, the organs exist. They still need to grow a lot bigger.) Baby is also already producing hormones from their pitutary gland, and their bone marrow is already producing white blood cells.
There's a lot of variance in "bump" sizes from person to person and pregnancy to pregnancy. Don't stress if you have no bump to speak of, or if you have a big bump already.
At this point, you might be trading first-trimester troubles for second-trimester troubles. Or possibly having both sets of problems at the same time. Do your best to make it through and keep up with any meds or other things that have been helping.
As your uterus gets bigger, it'll start poking up past your pubic bone. You might be able to feel it from the outside, and it might be a little sensitive. It will also stop pushing on your bladder so much, so you won't have to pee so often.
Nausea - You may have a resurgence of nausea this week, as there's a last spike of hormones around week 12. Take nausea meds if you need them - there's no rule that says you have to stop when you're getting to the second trimester.
Dizziness - Your body is working on creating extra blood to carry to your uterus and the baby. In the meantime, you may experience low blood pressure symptoms. If you start feeling dizzy, sit or lie down if possible. If you can eat something salty or drink something, it may help revive you a little.