Scansion and Iambic quatrain (workshop)

and through | the terms |strike dai|ly to| disperse
 my lax-|ness in-|to di-|sci-pline| and more

 “When I have FEARS that I may CEASE to BE…” (Keats) 

Remember that Iamb is a two syllable foot.

When I / have fears / that I / may cease / to be.

I have accented every other syllable here.

The second line is scanned correctly. Use that as your example.

Shall I comPARE thee TO a SUMmer’s DAY?”

Shall I / com-pare / thee to / a sum- / mer's day?

The third has the same problems in its scanning as the first. You are scanning what it sounds like in your head and not necessarily in Iamb.

As to the quatrain, it is flawless Iamb. Well done. Look in on my instructions on the main page and my example elsewhere here and move onto Trochee.

You did not scan incorrectly, you scanned differently. You read the second syllable of "daily" into the preposition "to" as a Pyrrhic which is common with a preposition. Prepositions are difficult to accent and when we try they tend to sound forced which is why (Ian, are you listening?) we try not to stress a preposition.
It was not a mistake. If we write a verse that can be scanned one way only it likely is rather dull with little natural rhythm. To produce a line of verse that is so flawless that it scans but one way and is yet natural and elegant is the height of our art:

To be or not to be that is the question.
There is a reason why this line is one of the most well known in the English language and even this is catalectic.