couldn't have been

Dear teachers.
I'd like to know the meaning of 1,2,3 and 4 in the next strory.
1. through thick and thin
2. pick things up
3. pitches in
4. I couldn't have been blessed with the best parents in the world!

My dad is always there when you have a problem. He loves all his children, their friends, but also his grandson. Through thick and thin my dad has always been there to help pick things up. All in all, this man is wonderful. He always pitches in around the house when mom is sick. He has shown to my brothers that men can do housework, too. Yes, he cooks, clean.
I couldn't have been blessed with the best parents in the world!

[Casiopea]

1. through thick and thin (the good times and the bad times)
2. pick things up (fix the situation, improve the situation)
3. pitches in (helps out)
4. I couldn't have been [more] blessed with the best parents in the world!