Which regime for eCommerce site?

I have been teaching guitar as an auto-entrepreneur since late 2009.  I made quarterly declarations of my income with URSSAF (BNC - enseignement culturel (8552Z)).

In July 2018 I moved from the Paris region down to Toulouse and stopped my ‘live’ teaching as I lost my clients.

I started producing video courses, eBooks and other printable products (which I assumed I could declare easily with URSSAF as it was still based around my teaching).  You can find this at - http://shop.rynaylorguitar.com

I have had issues with URSSAF after moving and it took several months before I was correctly registered with URSSAF Midi-Pyrénées.  I was therefore unable to complete my declarations and now have three paper declarations to complete (for the first three trimestres of 2019).

(I subsequently completed these declarations by hand but declared the eCommerce income as ‘vente de marchandise’ with the taux 13,80% - my cheque was accepted by URSSAF midi-pyrénées but it seems this might be entirely wrong!)

I was informed by a local accountant as well as the tax office that I would need to register with the CCI for my eCommerce activity.

I have done that and my ‘activité principale’ is now ‘Vente à distance sur catalogue spécialisé’ (4791B), which has been back-dated as
starting on 01/01/2019.

I was not sure how best to declare my revenue to URSSAF (BIC/BNC?) and requested clarification from them.  I am still awaiting a response.

URSSAF informed me by telephone that I need to close my account with them and register with the SSI (ex. RSI).

I am lost and really need some assistance to know whether that is correct and how I proceed.

I looked to make a declaration of my income for the 4e trimestre 2019 on the URSSAF site and I saw that the taux for vente de marchandises is 23,00% (and not 13,80% which I declared previously).  I have not completed this declaration yet because I really need to get everything sorted and in order before sending any more money to URSSAF.

I make most of my income from online sales, but also continue to teach (via Skype) and get revenue from Google AdSense and Patreon (a site where fans of my work can give a monthly pledge).

Please help!