Goals updated -- maybe I should try harder?

First off, about my journey: I lost 50lbs over the last year and a half, then gained back 15 over the holidays this year. Now I've lost 5 of those and am trying to get rid of the last 10 for good.

This morning I updated my goals and MFP said to lose 1lb/week I should have 1390 calories/day. For the longest time I was having 1200/day, and recently it's been 1400. So I'm wondering how much difference is 10 calories really going to make? Maybe I should tell MFP I want to lose 1.5 or 2lbs/week?

The thing is I'm concerned about making sure this is permanent, but at the same time I'd like to be at my goal weight for my birthday in 5 weeks. What do y'all think? Does losing weight more slowly really help keep it off? If I lose the weight more quickly and then set MFP to maintain, can I do it? Has anyone had much success maintaining on MFP?