After you file

Is the IRS still backed up with tax returns this year? I mailed out my federal return on February 23rd. I check the "where's my refund" tool daily and it doesn't have any information for me at all. I don't even know if they received my return yet. I'm not worried about waiting for my money if I know it will come eventually, I'm just worried my tax return was lost and I'm waiting for nothing. I know they stress to not file another return or to not even call the IRS. I just don't know what to do.