I have not used it myself but I have done tons of research on it because I have had issues here as well. Some claim almost immediate effects while others claim a week or two. The dose required is VERY small and is usually twice a week I believe. I'd have to dig up my research to be more specific, why don't you get a lab drawn and see what your prolactin levels are if you think that may be it?
Your E2 (or anything else) could be out of range as well just because you are taking an anti-e does not mean it's in range could be low, could be high, either would hurt your equipment.
5-7 weeks out is when your levels plateau (assuming you are on cyp or enanthate) so this would be the point that you would want things to come together, not fall apart.
Sounds to me like something is not right with your balance if it were me I'd get labs done, it's the only way you can know for sure.
If you mess with Dostinex it may only prolong your finding the true solution. My point being.....If you are in a state of hormonal balance you should have no need for Dostinex.
Just my 2 cents believe me I have been where you are, just trying to help out.
Of course there may be other reasons for your "issue" but at least this way you could rule out your hormonal balance and look elsewhere.