Is it possible that years of medication like, anti depressants & mood stabilizers and their side effects caused my ibs? How can I reduce IBS symptoms?

Caused or uncovered? Certain meds can aggravate or uncover ibs, which tends to have genetic roots. Chronic antidepressant and mood stabilizer use plus stresses of chronic illnesses themselves may be a double dose of ibs stress. Stress alone can trigger ibs. Reducing stress of mood disorders with meds that could awaken ibs is a mixed blessing but the illnesses without meds is worse. Consult a GI specialist for help.
COLLABORATION. It is the story of the chicken and the egg. In other words, i agree you should consult a GI specialist but stopping your current meds may not be the best thing to do. My advise is to have both phyicians collaborate with each other to provide treatment for both conditions as one may worsen the other or continuation or discontinuation of medicine may be necessary but requires mutual collaboration.