“I think” vs “I thought”
Use “I think”
1) To agree on something at the present but not totally sure.
Boyfriend: Do you love me?
Girlfriend: I think so.
2) To state an opinion or belief.
“I think you are beautiful.”
Use “I thought”
1) To talk about what you were thinking in the past.
“When I was teaching in high school, I thought of making this blog.”
2) To state a belief you no longer believe in or opinion you no longer have.
Wife: Am I beautiful?
Husband: I thought you were.
3) To confirm something you believed it was and is now a known fact.
Girlfriend: I admit you are not my first boyfriend.
Boy: I thought so. But I still love you no matter what.