... i am 6 weeks pregnant and we both agreed that i should deliver the baby there in canada. will it be ok if i apply for a trv to go there and file conjugal partnership in canada before i deliver the baby?
Because you got a TRV for Canada previously, you have a good chance of being able to get one again. Apply again using the same proof you used last time. Don't mention you are pregnant, and don't mention you are going to see your boyfriend (unless you said you were going to see your boyfriend on the last application; if it was accepted then it should be OK this time too.) Don't say you are thinking of applying for a PR visa while in Canada.
The problem is you need a medical for the PR application, which includes an x-ray, and pregnant women should not have an x-ray. Some doctors will do an x-ray very late in the pregnancy, but that will be too late for you to get the PR before the birth. So if you go to Canada soon on a TRV, you can start your application, but you will not have received the PR by the time you give birth, so you and your boyfriend will have to pay for costs of the birth yourselves. An uncomplicated birth costs around $10,000.
will the baby be able to use my boyfriend's last name?
In Canada, yes.
i sent him lots of letters and he sent me some letters too, we have pictures together on my visit to canada recently but he is not sending me money coz i told him i can support myself and my kids and i think its my pride that i dont want him spend for me also he works freelance and has no stable income.
You do not need to show monetary support for a successful application, but it does help.
will there be help for us when i deliver the baby in canada?
No, you will have to pay for your medical care until the baby is born.
he is also the one who sent the money for my ticket but he sent it through a friend who came to the phils for a visit. with the absence of monetary support, can we still convince the visa officer that we have genuine conjugal relationship?
You can get an affidavit from this friend stating these facts. However, to prove conjugal one good type of evidence is proof that your finances are joined, so him sending you support would be better if possible. Or, once you get to Canada, since you will be living together, you can join your inanaces as much as possible then. You won't be able to apply for a while (because of the pregnancy and problems with the x-ray and medical), so that will give you time to show that your finances are combined.