RSVP's - should I be concerned?

Unfortunately, it's normal lol

I'd give it a few more weeks until you're closer to the deadline. Other replies could still be in the mail, since it does take 5-7 days, depending on where it's coming from. People who have P.O. boxes don't check them everyday. People also wait until the last minute to send in RVSPs.

I wouldn't be too concerned, the week of your deadline, start calling people and asking if they send it in/if they are coming or not.

Totally normal. It has only been a month so you have to consider that; say you sent them out Feb. 14th (half-way), takes 5-7 days to get to them which brings you to Feb. 22nd (account for a Sunday). Then even if they sent their reply that same day you get March 2nd. So say people don't RSVP same day they get the mail or don't check their mail everyday (growing up we checked the mail only 2 or 3 times a week), then you should start receiving more by the end of this month.

With that in mind and considering when your RSVP deadline is, I would just say to sit back and wait, and then the week before your deadline start calling people up to make sure they have sent it in the mail.

I would wait till a week before april and see how they are coming in. Sometimes mail can take forever and people might not right away.

Totally normal!

I remember one wedding where, I was just SO BUSY (traveling, work/OT), that I had to add a reminder in my phone to RSVP by a certain date (2 weeks before the deadline).