First time mining and i would like to ask a few questions.

I tried mining for 3 days now with a rx580 8gb. What it bothers me is that i see different hash rate on the teamredminer and the 2miners pool site. Here is the hash rate from the app (?) https://prnt.sc/10q3a3g and here is from the site 2miners https://prnt.sc/10q3djn. My question is, why it is so different ? Like in the 2miners it has gone all up to 28Mh while on the app is maintaining a 10-11,4 Mh. Also some times it takes way more than 15-20 mins to accept a share, is that cause of low hashrate? Thank you if you have time to explain.