SSRI can be life changing for some people, in a very positive way. But definitely not for everyone or at the first time. Have a plan with your doc on what to do if things get worse, and if needed on how to stop taking the meds in a safe way.
2. Schedule a follow up
Maybe 1 month after you start taking the medication schedule a follow up to review the meds. You may need to change a couple of times before you have the right ones. Have a doctor who understand and agrees with this plan. Then schedule a follow up something like 6 months later and so on regularly maybe yearly if everything goes well. Don't see it as a one off thing. Psychiatric meds are often hit and miss.
3. Don't rely solely on meds
There are many interventions that help with depression, including psychotherapy, mindfulness, and lifestyle changes. All this should be considered for the success of the therapy. Meds at their best will help you with the change.
Also if you feel a tight stomach, after ruling out organic illness, you may consider massage therapy to help you with anxiety. Learning massage therapy actually helped me a lot.