postnatal depression ... please advise

I don't really know where to start explaining this so il say it how it is but apologise if it doesn't make sense as im exhausted right now. July 2015 i lost my little boy at 23 weeks 5 days old and i also lost a boy at 11 weeks old ( twin... his sister died at 2hrs old ). I was told via genetic testing i would never have another healthy baby and against all odds 8 weeks ago i gave birth to a healthy baby boy. He is the spitting image of the sons i lost and since having him ive done nothing but cry because all i can see is my sons i lost in him. I have become so protective i wont let anyone hold him except his dad and hate putting him down. Yes i know im making a rod for my own back but im so scared something bad will happen to him constantly. I am not sleeping even though i have a top monitor which will tell you if hes stopped breathing by alarm, too hot/cold, vomited, moved out of safety zone. I am watching him to eventually il crash out maybe for a few hours at most. I awake feeling bad ive fallen asleep. I am not eating much no appetite at all. Im pysically exhausted beyond words right now. Do you think im suffering anxiety and postnatal depression? Or just over tied and being silly? Ive had councelling for my losses and was doing fine until baby came. Not sure why its all come back to me now but im struggling to accept everything. Please advise and thanks for reading/commenting. Ps-- im too ashamed to ask for help incase the doctor or person thinks im a bad mother or even worse think i cant cope and try take my son. Excuse spelling/grammer im so tied.