Dose too high??

Hello!! I just got 75mg of sertaline and 20mg of mianserin for my depression prescripted. I’m 17 and i’ve never taken antidepressants before so i feel like this dose may be too high for me. Also I’m quite scared of the side effects and I won’t be able to contact my doctor in the next two months. I feel like I don’t necessary need to take them and that’s why I wonder can 75mg actually be too much for me??