Dear Mrs. Saranya,
Elders have suggested a very practical and most beneficial approach. Since you also wish to invoke the grace of God by mantras, I would like to share a few which my sister is saying now-a-days for the same cause.
She says the following daily: Garbha RakshambikaStotram, Mukundashtakam, santana gopala stotram
Puthra Prapthi ashtakam, Vamsa_Vrudhi_Kara_Durga_Kavacham
All these can be found in the website --> hindupedia / storas
The temples Guruvayur, Mannaarassala Nagaraja are the places she visited
thekeralatemples . com / knowmore / believe_it_or_not.htm
I hope you find it useful.
Regards,
Sneha