Though I am married according to my will now I am not happy with my husband. I want to know if this is some kind of divine punishment due to the fact that I was excessively picky to choose a boy when my parents facilitated suitors for my marriage?
Bismihi ta'ala
What you did previously in rejecting marriage proposals of suitors, even though they met all the requirements that a woman should need for marriage was wrong.
Making wrong decisions also tends to affect all of us when we grow up and become more mature. We regret our immaturity and realise how negatively influenced we were by our false ideas or unrealistic expectations. Islam points this out in many hadiths, stressing on what the criteria needs to be for spouse selection, and if one neglects these recommendations, they will face many problems.
It's very sad how we have distanced ourselves away from the teachings of Islam.
Allah ta'ala also reminds us every once in a while how we need to mould our lives around our religion, and not turn our backs against Him. If we turn away we become miserable. We start to become negative, and even though we are surrounded with blessings, we do not see any of them.
That being said, you should not blame your current situation on the past. You have free-will, and you choose your direction in life. You create your own mental state, and with your reliance on God and adherence to religion, you are able to have the best level of mental tranquility.
Do not think about punishment, or this unhappiness you are experiencing being because your past decisions creeping up on you, or karma, etc... This kind of thinking is not going to remove your unhappiness.
Try to focus on why you are not happy with your husband. Is it solvable. Are there things that you or him or both of you can do to keep the marriage. What are you able to do to make your relationship survive?
Maybe both of you should visit a marriage counsellor who can teach both of you skills to improve your marriage. Maybe you should see a therapist who can give you tips on how to become happy in your life and in marriage.
In any case, although you might have made wrong decisions in the past, it should not define who you are now, and you should not think of what you go through only as punishment from Allah ta'ala. Take control of your life and do the right thing.
Turn your previous mistakes into something positive and beneficial for others. Try to guide those around you and share your experience by informing others about marriage and spouse selection. All this will not just be forms of mental atonement, but also give you comfort that you are contributing to something good that other people can benefit from.
With prayers for your success.