I take Prothiaden and have done for a year or so - I am lucky that I get a good effect from a very tiny dose.
OH ( a doctor) was on an SSRI at one time and, after the first few days, found great benefit from it. He found the only way to start it was to cut the tabs into quarters and then gradually build it up to full dose one week at a time. He had no problems gradually coming off it when the time was right.
I have a friend who has been on Citalopram for many years following a cancer diagnosis (she still has the tumour, but needs regular chemo). It has allowed her to have a normal life in the face of all these traumas.
DD has been on them for many years - Citalopram again - and it has been a lifesaver for her. She has tried to reduce the dose unsuccessfully, but this does not matter as she feels fine on them and there is no reason why she should not continue with them.
I am probably a bit older than you, but have successfully knocked my depression on the head by adding in HRT - a tiny dose.
The advice from others here that it is a bit grim to start with and then it does the trick is quite correct. When you are depressed you forget what it feels like to be positive and cheerful, but it is wonderful when it arrives!
I do hope that you will get some help and be feeling better soon.