First, I own that very suit. Brooks 1818, Madison cut, navy stripe.
Next, while a solid suit is, in theory, preferable for an interview or presentation, as a practical, real world matter your suit is fine. It's conservative, business-like, traditional. If you don't get called back for a second interview or don't get asked to give a presentation at some future conference, it won't be because you wore the suit, okay? So don't worry about it; doing so will only cause you to second guess yourself, which will leave you feeling less confident when wearing it, which actually can be a problem.
All this having been said, the next time you're shopping for suits, pick up one or two solids. A solid navy and a solid medium-to-charcoal grey would be the obvious choices, assuming you don't already have those bases covered. Not because a conservative stripe is necessarily a problem, but because an argument could be made for a solid navy and solid medium-to-charcoal grey as being the classic "core" of a professional, conservative, business suit wardrobe. (Naturally, you'll want more than a single suit, no matter how nice, if you anticipate wearing it for interviews, at conferences, and so forth.)
But again - your suit will be fine. DO NOT worry about it. You did well in choosing it. Assuming the alterations leave it fitting you well, wear it and forget about it. (That's the real role of a conservative business suit, anyway. That you can put it on and forget about it, knowing that you've successfully addressed the suit issue. Ideally, the people with whom you're meeting - in an interview, at a conference, etc. - won't even have any clear memory of exactly what you were wearing. It'll be so "spot on," that they won't focus on it in any way, but will instead focus on and remember you, not your clothing.)