Who told you that not yet having children is due to Manglik horoscopes? It is to be analysed by looking at the fifth house of a person’s horoscope. Manglik is a term used frequently by Astrologers to frighten the public. In fact most mangliks do not have in real sense this dosha. That is because there are more exceptions than rules. In your case you are really a Manglik.
Your fifth house which signifies happiness arising out of children is below average with a strength of 31.95% and your marital happiness house the 7th has a strength of only 30.23%. That is the reason for your infertility. At the age of 37+, and having no medical reasons for that, God only can help you and invoking that is not in the domain of Astrologers but within yourselves only. Read my articles on Remedies in http://navagrahastro.blogspot.in/.
If you need a detailed analysis of your horoscope, you can contact me.