I would definitely like to hear more, Amna. On one hand, 19 feels young to me as someone in my 30s; my views as a 19 y.o. are not necessarily my views now. On the other hand, perhaps I was less cluttered back then, more able to look within myself clearly than with all the attachments of being a husband, father, co-worker, etc. pulling on me.
To some degree, the feeling of certainty after shahaddah sounds little bit like the psychology of cognitive dissonance -- that is, one convinces himself or herself that the choice made was the right one. That's not to say the choice wasn't the right one, but the mind may artificially amplify that evaluation. I'd like to avoid that, if possible.
Could you tell me more about the opinion of people who surrounded you? I don't want to be swayed by others, of course, but I also want to be realistic in terms of how others might see this sort of decision.
The cognitive dissonance reference could be true in many people. I waiting until I was positive that it was what I was doing, the main thing holding me back was my family. I've always been the "problem child", and didn't want to disappoint the parents anymore (I had "straightened up" around 10th grade).
I received no pressure from the Muslims surrounding me. They were extremely willing to answer questions and provide more materials as needed. I talked extensively with Catholic priests, Mormon missionaries, and less with other religious leaders while making the decision. They obviously all attempted to dissuade me, but in the end, their arguments guided me closer to Islam. I have some friends who don't provide an opinion on my conversion, but there are a multitude who expressed disapproval... including my parents. To be honest, if the people who surround you are uneducated on Islam, probability of them readily accepting a reversion is quite low. My mom has begun to read and learn more about Islam, insha'Allah she will continue. I would suggest preparing them slowly, but trying including an "interesting fact" about Islam during regular conversations and/or discussions now. This does not commit you, obviously, but it will help pave the road for their education and acceptance of your reversion (if you decide to do so). Does this make sense?
Where are you located, by the way?