I think u have to decide if you are willing to put up with the breakouts and redness/irritation for a few months if it means you will have clearer skin indefinitely after (provided you still use tretinoin to maintain it).
I have been on isotretinoin before on a low dose course and it took over 9 months for me to have clear skin, so don't lose hope. In the first few months, I like yourself was wondering if it is actually worth the wait as my skin seemed to take forever to show major improvements. In the end after the 9-10 months I was delighted with the results.
The thing you have to remember is tretinoin and other retinoids DO work, but the changes are so subtle we don't see big changes at once, it just happens slowly until you reach the day when you see an overall improvent.. And I'll tell you it's worth it.
Remember good things come to those who wait