According to "Received Time", you sent it 2 days ago (not 5 days ago).
- I thought that dynamic fee would calculate the appropriate fee, then why do i have the message "low fee" ?
Most likely you forgot to bring the slider to the most right side (even if you've checked the use dynamic fee option) and as result, ended up with "low fee" status.
It's not out of order but rather limited to maximum of 100 transactions per hour. Just keep trying it.
Actually it goes up and down throughout the day but before the recent incidents (massive unconfirmed transactions going beyond 100k), it usually was on an average from 30k to 60k range at most.
- When will the network forget my transaction, how long can it last ?
Around 72 hrs.
- Does someone have any tips for me ?
Contact some users to help you out by including your transactions in a block, in exchange for some fees:
1. kano: https://bitcointalk.org/index.php?action=profile;u=360442. macbook-air:
https://bitcointalk.org/index.php?action=profile;u=16114
Furthermore read this thread:
https://bitcointalk.org/index.php?topic=1802212.0