Welcome to the forum!
I recommend you to download the free meditation course which gives great instructions.
My favourite book is by Paul Wilson - called The Quiet - it deals with three main approaches to meditation and lots of good advice.
It is conceivably possible that your antidepressant medication may affect your meditation experience - but as you have no benchmark to measure it against, I think it would be irrelevant.
I may be wrong, but from your post it seems like you may have some idea about what a 'meditation experience' would be like?
Meditation experiences vary wildly between meditators and also from session to session for each individual meditator. The experience you have in any meditation session is neither good nor bad - it just is. What is important is that you don't react to it.
Meditating brings up all sorts of stuff from deep inside. It brings it to the surface so that we can deal with it in a better way than when it got put in.
The way to deal with it in meditation is just to be aware of what is happening, just as an observer.
An unconcentrated, agitated meditation session can be a great sign that stuff has come up. If we can just accept that this is the way it is just now, the 'stuff' will lose all its oomph and we will will be a little lighter.
As you are taking anti-depressants, it is important that you go slowly while you are finding your feet in meditation. Start with ten minutes at a time and see how you go. If after a week, you feel you are handling it well and it is too little add another five minutes.
Keep us posted!
Hope this was helpful
peace and joy
