What a lot you have taken on very early in life! I hope your conversion gives you joy. I wish you the best in your marriage. Young marriages can work as long as both people are really, really committed to it and work on it when the going gets rough. Good for you for looking for help.
I can think of at least a couple of possible explanations for your drop in sex drive. Yes, it is indeed possible that getting sexually active is stirring up old issues around having been molested. It may be that you dealt with your feelings of betrayal and hurt by deciding that such things don’t happen to you outside of family. Now that you’ve brought your husband inside the family, he may seem more sexually dangerous to your unconscious self. Another possibility is that you have taken on too much change too fast and you haven’t been able to fully adjust. Shutting down sexually may be your way of slowing things down a little so you can manage. There may also be yet another reason that I don’t have enough information to comment on. From what you shared, I don’t think depression is the problem but there may be more to it than you could put in a letter.
I suggest you find a therapist who is sympathetic to women’s issues and who also is familiar with Islamic teachings about marriage and sex. Therapy might be more helpful if you got your husband involved from the start. From what you said, I don’t think either of you has a mental illness. It’s more likely that you are in a new phase of your relationship and you both need some pointers about how to support one another and be there for each other – particularly if old and painful issues may be rising to the top at the same time.
I wish you well.