First of all, you should not be stressing out and doubting your work. This is the easiest way to undermine success. You need to have faith and let Spirit take over. I have always had the best success when I simply do the work and then forget about it. I'm sure that others here would agree.
Sending a dressed card is traditional work, but I can see why he would be suspicious since you didn't write anything in it. It was indeed a "mystery card" so it's not surprising that he would now be trying to solve that mystery. Some times we address the card to a different person or write something vague like "thank you for your thoughtfulness" and leave it at that. It can then come across as misdirected mail, which is less likely to arouse suspicion than a blank message. The goal is to get him in contact with the dressed mail, with as little collateral suspicion as possible. Just a thought.
Regarding your doll baby and Follow Me Boy, the work takes time. You can't expect instantaneous results. Please have patience and faith. If you need more clarity in terms of what he might be up to with another woman, consider getting a reading.
You can certainly dress his door handle while he is away. If you know for a fact that he is not at home and don't want to draw attention from the neighbors, you could always pretend to knock on the door and while you are awaiting a response, rub some oil (lightly!) on the door handle. I like to dress the palm of my hand ahead of time for this purpose. You then just walk away when it's clear no-one is home. If you are more concerned about being identified by the neighbors, do this late at night when they are likely to be sleeping.
Hope this helps.