I am not sure if you can still claim... Maybe yes, hehe just ask hehe malay natin hehe...
opo, just visit the SSS main website also, you can download the forms there:
To notify that you will be giving birth use form MAT 1, then MAT 2... just read the guidelines carefully.
Also, if your civil status is still single according to them also, you dont have to worry. When submitting the Mat1 Form just bring with you your Marriage License and passport etc... so they could amend that on their system...
P.S.
A very reliable family member in the Philippines will be such a great help... My good-old-mother is doing all these things for me. When I visited there last year, I have signed an SPA (special power of attorney - but with certain limitations)...
Also, hehe I am promoting the Pinoy Radio Presentor in Norwich, She is a member here... It is a very good radiochannel (online if u r outside Norwich). You can asks lots of legal things etc...