I feel like my new crowns (front 4) are causing a lisp and resting on my bottom lip feels very unnatural. Is this wrong? (photo)

If the teeth are positioned wrong or the size is very different than what you had, it would cause the symptoms that you have. The best way to have dealt with this would have been to have you wear temporary crowns made off of the proposed crowns that he was planning to place. You would be trying those for sometimes and both you and your dentist would have seen if you could get used to it. Modifications could have been done to the temporary crowns if they were needed. Finals crowns would have been made off of the proven temporary crowns. 

I cannot see much from your right photo, but from the left photo, crowns do appear within normal limits for what we call overbite and overjet...how far the teeth overlap the lower teeth, and how far out they are.But  are they in correct position for YOU?  The way I as a cosmetic dentist treat this situation, if you were my patient seeking crowns, is to do a few tests on your speaking and tooth position BEFORE anything is done. Do they hang over your lip, are they out in a buck position , are they too short and no teeth show when you smile? This is the first thing that must be done with your own teeth. Then, WHAT IS THE PROBLEM we want to correct? Before Photos of all, front view,side view, and with lip in a relaxed positition.Then temporary crowns are made, correcting what I've tried to correct for you. Question for you? Were all of these steps followed? How did your temporary crowns feel? Were they made nicely, that your lip could feel the edge, could you speak correctly, and did they look nice when you smiled? I work out ALL of these things in temporary crowns, until they FEEL AND LOOK almost perfect. That's how I know the exact length the permanent crowns will be. And also, how they hit your lip, and if they are comfortable for YOU. I tell my lab all of these parameters, send them photos of you with your new temps, and even a model of the temps in your mouth.thats how cosmetic dentists eliminate all the guesswork. If we just flew by the seat of our pants, most of out patients would not get the benefit of our knowledge, and get what I call "crowns that look like they came right out of the box...chicklets...or look like you are wearing someone elses's teeth!!! Not customized for you!GOOD NEWS... Sometimes, just rounding back that lower edge, in you mouth can help the problem. Also, hitting the lip can mean they are too long. That is a simple fix. The dentist just very carefully shortens the teeth, after checking all of the tests I mentioned above.So if you like them, it may only be a matter of a simple adjustment of contours that can be done on a return visit. Also, sometimes cheap means cheap. Corners are cut, temps look terrible, with the promise that the real ones will look great, etc etc. Front teeth, crowns or veneers are what make our smile. They give us character, and a pleasing or not pleasing smile.THEY HAVE TO BE DONE WITH SPECIAL CARE, AND LOOK GOOD ON YOU!

Thanks for posting your photos. Without a before picture it's difficult for me to determine the changes that have occurred. From what I see your teeth don't appear to protrude excessively and the length looks within normal limits. Closing the space can cause changes in your speech. I would encourage you to give your new restorations a little more time. If you can't get used to your new restorations let your dentist know. They want you to be happy. They may be able to adjust the length and contours without redoing the restorations. The most important thing is to keep an open dialogue. Good luck with your new smile.