Refund delay

The IRS accepted my 2020 return on Feb. 19, 2021.  As of May 5 I have not received my refund or stimulus.  There are several issues with my refund that may cause the processing delay.  However, I am concerned that there might be an error on my return  and/or I may have been sent a notice that I did not received.  I changed my mailing address twice after I filed and some of my mail may not have been forwarded or may have been discarded if it went to the wrong address.  I have found no way at all to get through to any direct assistance that could help with this specifically or any information that says more than "your return is being processed".  Any advice?