Feeling ashamed of one's past

Q: I am really worried about something which I did 1-2 year ago. I was 16 years old and sexted with a married woman. She sent me a photo of her breasts twice. I felt so guilty and sick of myself and cut all contact with her. I am ashamed of what I did. My imaan wasn't that strong back then. I am a born muslim and I just remembred about it today. I think first time was one night in the holy month of Ramazan and second time later. What should I do? Will Allah Ta'ala forgive me for my shamefull sin? 

Betting

Q: Is trading halal? Like the website I am using is IQ Option. Where you bet the price on 4th decimal of the rate.

Bleeding after nifaas

Q: I recently had my 3rd baby and on the 25th day started prayers after taking ghusl as the bleeding had stopped. But on the 40th day the bleeding started and thinking that periods have started I stopped praying but the bleeding stopped by evening. I waited one day to confirm and when the bleeding didn't come took ghusl and started praying. But after 2 days again the bleeding started. This time also it stopped by evening. I have not yet taken ghusl as don't know what to do. Please let me know if it's nifaas or haiz or something else. And should I wait further or take ghusl and start praying? What about prayers missed?