Since + to be(part 2)?

Hi, dear teachers. In this part "since" is followed by a prepositional phrase. These sentences are found on fraze.it.

1. Amy Norton has saved $10,000 to get her Seattle bedding company off the ground and has been working on the idea for more than a year, since just after she and her now-ex husband separated. Although she did not work during her marriage, she says, “I have always been a creative person and had a nagging desire to do something entrepreneurial. Plus, I haven’t been in the workforce for 17 or 18 years, and the whole thing has changed since I was there. I wonder if maybe I don’t have the skills to offer in a formal business setting anymore.”

I think this sentence means "The whole thing has changed since I left Seattle" Am I right?

2. The argument about whether homework is worthwhile has raged since I was at school. It's true that homework given without a clear purpose can be confusing and sometimes demotivating for students. I remember one of my own children in Year 3 being given a piece of homework which was "write a story". His first reaction was to ask my wife and I what he should write about.

I think this sentence means "The argument about whether homework is worthwhile has raged since I left school. The argument is still ongoing now though I am no longer at school." Am I right???

3. He has been competing for many years, since he was in preschool in Stokes County.

I think this sentence means "He has been competing since he became a student in preschool. He's long since left preschool but he is still competing." Am I right?

4. ... I got everything settled down, I decided I still wanted to play somewhere that I could have fun.I haven't had fun playing football since I was in college. I didn't want to have to worry about the crazy side of playing football that comes with playing in the...

I think this sentence means "The last time I had fun playing football was at some time during the time when I was still in college. I may have quit playing football when I was a junior or senior. After that up until now, I haven't had fun playing football." Am I right?

5. I will soon be shopping with my granddaughter, age 13, for her back-to-school clothes.I haven't done this since my own daughter was in school. I don't know what is in fashion for young teens and what is appropriate. Also, we are on a very tight...

I think this sentence means "The last time I did this(shopped) was at some time during the time when my own daughter was still in school. The last time could have been her last year in school or her second year in school. But anyway, I haven't done that since then". Am I right?

Would you please check my interpretations? Thank you in advance.